NATIONAL CENTER Series 4 

For HEALTH STATISTICS INumber 12 

VITAL and HEALTH STATISTICS 

DOCUMENTS AND COMMITTEE REPORTS 

. 

f%opER~~F~ -

PUBLICATIONSBRANCH 

EDITORIALLIBMRY 

Needs for 

NationalStudiesof 

PopulationDynamics 

A Report of the United States National 

Committee on Vital and Health Statistics 

An assessment of the types of studies needed in the field of 

population dynamics, the specific types of data needed to 

yield such studies, and the steps required to meet these 

needs most effectively. 

U.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE 

Public Health Service 

Health Services and Mental Health Administration 

Rockville, Md. April 1970 
Public Health Service Publication No. 1000-Series 4-No. 12 

For We by the Superintendent of Documents, U.S. Government Printing Office, Washington, D. C., 20402- Prko 4fiwmts 
NATIONAL CENTER FOR HEALTH STATISTICS 

THEODORE D.W()()JJSEY,
 DiTeCtoT 

PHILIP S. LAWRENCE, SC.D., Associate Director 

OSWALD K. SAGEN, PH.D.,, Assistant Director for Health Statistics Development 

WALT R. SIMMONS, M.A., Assistant Director for Research and Scientific Development 

Medical Consultant 

JAMES E. KELLY, D. D. S., Dental Advisor 

EDWARD E. MINTY, Executive O//icer 

,! 

MARGERY R. CUNNINGHAM, Information O//icer 

OFFICE OF HEALTH STATISTICS ANALYSIS 

IWAO M. MORIYAMA, Ph. D., Director’ 

DEAN E. KRUEGER, Deputy Director 

Public Health Service Publication No. 1000-Series 4-No. 12 

Library oi Congress Catalog Card Number 75-605824 
FOREWORD 

Marked changes continue with respect to the size, distribution, 

and composition of the Nation’s population. This dynamic nature of 

the U.S. population is a consequence of varying patterns in family 

formation and dissolution, fertility, mortality, and m~~ation. 

The central purpose of this report, prepared under the auspices 

of the U.S. National Committee on Vital and Health Statistics, is to 

call attention to the “types of studies needed in the field of 

population. dyna&ics, the specific types of data needed to yield such 

studies, and (to make) suggestions as to how such data might best be 

collected.” Suggestions are made for systematically augmenting the 

usefulness of the existing data sources, and where most essential, 

certain new data sources are recommended. 

Forrest E. Linder, Ph.D.


Chairman


U.S. National Committee on


Vital and Health Statistics


,,. 

nl 
U..% NATIONAL COMMITTEE ON VITAL AND HEALTH STATISTICS 

Forrest E. Linder, Ph.D., Chairman


Professor, Department of Biostatistics


School of public Health


University of North Carolina


Chapel Hi~, North Carolina


Iwao M. Moriyama, Ph.D., Executive Secretary


IXrector, Office of Health Statistics Analysis


National Center for Health Statistics


Health Services and Mental Health Administration


Public Health Service*


Rockville, Ma ryland


Donald J. Davids ‘


Chief, Records and Statistics Section


Colorado State Department of public Health


Denver, Colorado


Kingsley Davis, Ph.D.


Director, International Population and


Urban Research 

Professor of Sociology


University of California, Berkeley


Berkeley, California


William R Gaffey, Ph.D. 

Senior Biostatistical Consultant 

Pacific hledical Center 

San Francisco, California 

Herbert E. Klarman, Ph.D. 

Charles E. Lewis, M.D. 

Professor of social Medicine and 

Assistant Director of the Harvard Center 

for Community Health and Medical Care 

Boston, Massachusetts 

I 

1 Abraham M. Lilienfeld, M.D. 

professor and Chairman


Department of Chronic Diseasm


School of Hygiene and public Health


The Johns Hopkins University


Bakimore, Maryland


Robert parke, Jr,


Program Planning Officer


Bureau of the Census


U.S. Department of Commerce


Washington, D.C,


John R. philp, M.D.


Health Officer


County of Orange Heakh Department


Santa Ana, California


Donovan J. Thompson, Ph,D,


Professor, Department of Preventive Medicine


School of Medicine


University of Washington


Seattle, Washington


Theodore D, Woolsey, ex officio


Professor, Department of Environmental Medicine and Director, National Center for Health Statistics 

Community Health Health Services and Mental Heakh Administration 

Downstate Medical Center Public Health Service*


State University of New York Rockville, Maryland


Brooklyn, New York


Paul Kotin, M.D.


Director, National Institute of Environmental Sciences


National Institutes of Health


Public Health Service*


Research Triangle Park, North Carolina *t)epartmentof IIealth, Education, and Yi’elfwc 
CONTENTS


Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Introduction ”,, , .,..,,.,, ,, .,, ,,, . ., .,..,....


Statistics Needed for the Systematic Study of Marriage and Divorce.


Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


The Incidence of Family Formation and Dissolution , , . . . .


The Prevalence of Different Marital Status Groups . , . , . . .


The Relationship of Marital Status to Fertility . . . . , , . . ,


The Relationship of Marriage and Divorce to Migration . . . .


Sources of Data and Recommendations , . . . . . . . . , . . .


Fertility and Family Planning . . . . . . . . . . . . . . . . . . . . . .


Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


Natality Statistics...,,.,,. . . . . . . . . . . . . . . . . .


Intervening Factors.,.,,,.. . . . . . . . . . . . . . . . . .


Relationship to Background Variables . . . , , . . . , . . . . .


Sources of Data . . . . . . . . . . . . . . . . . . . . . . . . . . .


Recommendations . . . . . . . . . . . . . . . . . . . . . . . . .


Migration ., .,, .,,,,,.,. . . . . . . . . . . . . . . . . . . . .


Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


The Factors that Influence Migration . , . . . . . . . . . . . . .


Sources of Data . . . . . . . . . . . . . . . . . . . . . . . . . . .


Migration Questions that Need to be Studied , . . . . . . . . .


Recommendations . . . . . . . . . . . . . . . . . . . . . . ...23


... 

Ill 

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5 

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6 

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19


21

Page 

Role of Mortality and Morbidity in Population Dynamics . . . . . .


Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


Component of Population Change . . . . . . . . . . . . . . . .


Completed Fertility . . . . . . . . . . . . . . . . . . . . . . . . .


Early Pregnancy Terminations . . . . . . . . . . . . . . . . . . .


Health and Migration . . . . . . . . . . . . . . . . . . . . . . . .


Health Consequences of Population Change . . . . . . . . . . .


Recommendations . . . . . . . . . . . . . . . . . . . . . . . . .


Overview o.. .eo. ..e o... .. OF . . . . . . . . . . . . . . . .


References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


24 

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25 

25 

26 

26 

26 

26 

31 

vi 
SUBCOMMITTEE 

Clyde V. Kiser, Ph.D., Chairman


Vice president for Technical Affairs


Milbank Memorial Fund


NCWYork, New York


John E, Patterson, Secretary


Chief, Natalit y Branch


Division of Vital Statistics


National Center for Health Statistics


Health Services and Mental Health Administration


Public Health Service*


Rockvi he, Maryland


Donald J. Bogue, Ph.D.


Director, community and Famfly Study Center


University of Chicago


Chicago, Illinois.


~thur A, Campbell


Deputy Director, Center for Poptdation Research


National Institute of Child Health and Human


Development 

National Institutes of Health* 

Bethesda, Maryland 

Leslie Corsa, Jr., M.D. 

Director, Center for Population Planning 

School of Public Heakh 

University of Michigan 

Ann Arbor, Michigan 

ON POPULATION DYNAMICS 

Oscar Harkavy, Ph.D.


Director


Population Program


Ford Foundation


New York, New York


I. M. Moriyama, Ph.D. ex officio


Executive Secretary,


National Committee on Vital and Health Statistics


Natiomd Center for Health Statistics


Health Services and Mental Administration


public Health Service*


Rockville, Maryland


Robert Parke, Jr.


Program Planning Officer


Bureau of the Census


Department of Commerce


Washington, D.C.


Robert G. Potter, Jr., Ph.D.


Professor


Department of Sociology and Anthropology


Brown University


providence,


Rhode Idand


*Departmentof Health,Education,andWelfare 

vii 
IN THIS REPOR T a Subcommittee of the U.S. National Cbmmittee 

on Vital and Health Statistics presents its findings on the principal 

needs for improvement in the statistics on population dynamics for 

this country and offers proposals as to how these needs might best be 

met. Recommendations are made relating to statistics on marrtige 

and divorce, fertility and family planning, migration, and mortality 

and morbidity, and to the role of these factors in the stud.v of 

population dynamics. The reibtionships between census and vital 

statistics data are examined, and suggestions are made for improving 

these data in relation to each other. The Subcommittee also suggests 

some ways in which various agencies of the Federal government 

might contribute more effectively in the collection, improvement, 

analysis and dissemination of demograph ic data. 

... Vlll 
NEEDS FOR NATIONAL STUDIES OF


POPULATION DYNAMICS


INTRODUCTION 

As in other countries of the world the population of the United States 

is highly dynamic. It has undergone, and it is still experiencing, marked 

changes with respect to size, distribution, and composition. These changes 

are the consequences of past tre~ds and differentials in fertility, mortality, 

and migration, the components of population change. 

The Subcommittee on Population Dynamics was given the responsibility of “preparing a report on types of studies needed in the field of 

population dynamics, the specific types of data needed to yield such studies, 

and suggestions as to how such daia might best be collected.” 

In preparing the present report the Subcommittee has endeavored to 

adhere entirely to the spirit, and in essential respect to the letter, of its 

charge. It was asked to “feel free to make recommendations regarding any 

phase of population dynamics [but to] consider the factors of reproductive 

behavior and the related variables to be its area of chief concern.” 

Accordingly, the first two of the four substantive divisions are devoted 

respectively to statistics on marriage and divorce, and on fertility and family 

planning. The section on marriage and divorce emphasizes the importance of 

including all States in the Marriage and Divorce Registration Area and 

discusses the possibilities of securing data from special surveys and the 

censuses until the use of the standard certificates of marriage and divorce are 

more widespread. 

The section on fertility and family planning discusses needed natality 

statistics, needed studies of “intervening factors,” (fecundity, reproductive 

norms and family planning practices) and the relation of the foregoing to 

factors such as race, religion, and socioeconomic status. 

The next two substantive divisions are concerned with the remaining 

components of population change, migration, and mortality. That the space 

devoted to migration may be larger than that envisaged in the charge seems 

justified in view of the important relation of migration to changing size and 

composition of metropolitan populations in recent years. In the section on 

mortality, recommendations for future studies were deliberately restricted to 

those believed to have special relevance to population dynamics. 

1

Finally, the “Overview” discusses the implications of the Subcommittee’s findings for the collection and analysis of data by government 

agencies. It. is hoped that this report will serve not only to point up needs for 

research in population dynamics but also to suggest some ways in which 

various agencies of the Government might contribute more effectively in the 

collection, improvement, analysis, and dissemination of demographic data. 

STATISTICS NEEDED FOR THE SYSTEMATIC STUDY OF 

MARRIAGE AND DIVORCE 

Introduction 

The family performs many functions that 

are directly relevant to population dynamics. It 

is the primary institution into which children 

are born and prepared for adult life. It is the 

only social grouping that man usually takes 

with him when he moves. Because of the 

importance of this basic institution in shaping 

the growth and distribution of our population, 

statistics on family formation and dissolution 

are essential to an adequate understanding of 

the nature, determinants, and consequences of 

population dynamics. However, data now available are not sufficient to measure trends or 

differentials in various phenomena associated 

with the family, This section presents a description of the statistics needed for these 

purposes. 

The Incidence of Family Formation 

and Dissolution 

At present, statistics are not available on 

such elementary variables as the ages of brides 

and grooms and of divorcing partners for the 

country as a whole. The available data consist 

of total marriages and divorces for each State 

and a few variables such as age, race, and 

number of times married for the States in the 

Marriage and Divorce Registration Areas. Even 

in some of these States, the reporting of certain 

characteristics is very poor. 

In 1968, the Marriage Registration Area 

was comprised of 39 States and the District of 

Columbia and covered about 7’7 percent of all 

marriages. The Divorce Registration Area, llowe{er, consisted of only 26 States and covered 

only 56 percent of all divorces. A concerted 

effort should be made to include all States in 

the Marriage and Divorce Registration Areas, to 

improve reporting in certain States, and to 

encourage the adoption of the standard certificates of marriage and divorce. Only after these 

actions are taken will there be an adequate 

statistical base for the study of trends and 

differentials in marriage and divorce. 

Meanwhile, some steps might be taken as 

interim measures to fill some of the gaps in our 

knowledge. One would be the development of a 

method of estimating current annual numbers 

of marriages for the entire United States, 

classified by age of bride and groom (showing 

single years of age), by race of bride and groom, 

and by whether or not the marriage is the first 

for the bride and g;oom. If similar estimates 

could “also be prepared on the basis of frag- ­

mentary evidence available for the past 40 

years, it would be possible to estimate cohort 

first marriage rates (that is, first marriage rates 

for groups of women called “cohorts,” iden2 
tified by the year of birth of the women 

included in them). These rates would be extremely useful in the study of trends in age at 

marriage and in relating trends in marriage and 

fertility rates. Such a set of estimates was 

prepared by the Scripps Foundation for Research in Population Problems for the period 

1917-1960, but an updated and improved series 

could, and should, be developed. 

The limited data now available could also 

be substantially improved by using smoothed 

population estimates, by age, in the computation of age-specific marriage rates. The 

Bureau of the Census and the National Center 

for Health Statistics (NCHS) should coordinate 

their efforts to base rates on population e% 

tirnates that are free of the year-to-year variations caused solely by sampling error. 

It would also be desirable to use current 

data to prepare attrition tables for cohorts of 

married men and women, by race, showing the 

effects of divorce and death of spouse on 

numbers of married couples, but the information needed to prepare such tables is probably 

fragmentary and too unreliable to make it 

possible. 

It would, however, be possible to estimate 

probabilities of divorce by duration of marriage 

on the basis of surveys such as the Survey of 

Economic Opportunity of 1967, and every 

advantage should be taken of such opportunities. 

Until the standard certificates of marriage 

and divorce are in widespread use, it will be 

necessary to rely on data from surveys and 

censuses for information about socioeconomic 

differentials in marriage and divorce. At the 

ptesent time, marriage and divorce registration 

data give very limited and fragmentary information on differentials by only one socioeconomic characteristic: race. In some States 

even this item is not reported. This is quite 

inadequate for a satisfactory understanding of 

the reciprocal relationships between socioeconomic status and family formation and 

dissolution. It is true that educational attainment is now on the Standard Certificates of 

Marriage and Divorce or Annulment and is 

being added to the certificates of a few States. 

Unt~ this item is more widely used in marriage 

and divorce reporting, however, efforts should 

be made to add questions to nationwide surveys 

that will give additional information about the 

incidence and age patterns of marriage and 

divorce in different socioeconomic groups. 

A marriage followback survey would provide a great deal of data that is currently 

lacking.a Such a survey can supply not only a 

great deal of needed information about the 

characteristics of the bride and groom, but also 

information that will be helpful in the analysis 

of trends in fertility. For example, a marriage 

followback survey could contain questions on 

the expected timing of the first birth and on the 

couple’s current use of contraception. Useful as 

such a survey mechanism would be, it should 

not be considered as a substitute for a nationwide marriage registration system. 

Followback surveys on divorces likewise 

could provide useful information. Such a survey 

program would undoubtedly be more difficult 

to administer than a marriage followback survey 

because the divorced partners would have different addresses and might be difficult to 

locate. However, a feasibility study of such a 

survey should be considered, to find out what 

kinds- of information could be obtained. As a 

aA gollowback s.u~ey is one which uses a kno~ 

event such as a birth, death, marriage, or divorce which 

is recorded on a legal document as the sampling frame 

and then goes back to the person who was the 

informant on the original document for additional 

information. Such a survey can also use other informants 

who may have knowledge of the event as sources for 

information. 

3 
minimum, there should be considerable information on the socioeconomic characteristics 

of the divorced partners and of their. past 

fertility experience. 

The Prevalenceof Different Marital 

Status Groups 

As noted above, data from censuses and 

surveys can provide a great deal of information 

about the incidence of marriage and divorce and 

of the age patterns of these phenomena in 

different socioeconomic groups. In addition, 

these census and survey mechanisms are the 

only ones that can provide reliable data on the 

prevalence of various marital status groups. 

Efforts should be made to obtain more 

information on marital status categories than is 

now available from most survey sources, For 

example, it is evident that many’ men and 

women live as husband and wife but are not 

married. U would be very helpful in relating 

nationwide statistics on marital status to fertility if these statistics at least occasionally 

included a category “consensual unionf’ this 

category is now used in some statistics for 

Puerto Rico. 

There is considerable interest in determining how many men and women in various age 

groups had been divorced at some previous time 

but are not currently classified as divorced. This 

information would provide a count of the 

ever-divorced similar to the count now available 

of the ever-married population. 

Marital status histories obtained in nationwide surveys, such as the Current Population 

Survey, would provide a considerable body of 

valuable data, including information for large 

numbers of people on the ages at which first 

marriages occur and the timing of subsequent 

events, The items of information could include 

selected characteristics of each former spouse 

(for example, age, race, and education). Such 

marital status histories could be used in connection with fertility histories of individuals, 

particularly women. They would make it po~ 

sible to assess the interaction of marital status 

and fertility over relatively long periods of time. 

Marital status histories would also be valuable in 

supplying information on illegitimate births to 

currently married and formerly married women. 

The principal available source of data on illegitimate births-the birth certificate-indicates 

only whether or not the birth is legitimate or 

whether or not the mother is currently married. 

There is no information on the mother’s marital 

history. 

The Relationship of Marital Status 

to Fertility 

One area about which a great deal of 

additional information is needed is the relationship of premarital pregnancy to marriage. In 

exploring this relationship in Detroit, William 

Pratt showed that a large portion of the color 

difference in illegitimate fertility could be 

explained by the different propensities of white 

and nonwhite girls to marry after becoming 

pregnant.1 Although this study was extremely 

useful, jt has never been repeated elsewhere. 

Birth records and marriage records could be 

matched in certain areas where the appropriate 

information is available. 

Similar information could be developed 

for the nation as a whole, if there were a place 

on the birth record to record the date of 

marriage of the parents. This item, however, 

was specifically rejected in the process of 

drafting the 1968 Standard Certificate of Live 

Birth. Some information on the relationship 

between premarital pregnancy and marriage 

might be obtained from the Natality Followback Survey, although the sample would be 

very small for the group involved, 

4 
Another area about which little is known 

is the relationship of fertility to marital dissolution and remarriage. For example, it is not 

known whether remarriage tends to increase 

fertility because the newly married couple 

wants to have children of their own or whether 

the net effect is to reduce fertility by reducing 

the number of years that a woman spends with 

a husband during the reproductive years of life. 

Questions of this kind could be explored with 

the use of marital histories from surveys mentioned above. 

There is still a great deal that is not known 

about the relationship of age at marriage to 

fertility. For example, there are no current 

statistics from the registration system on the 

average number of months between marriage 

and the first birth. The addition of date of 

marriage to the birth certificate would provide a 

basis for securing kformation on this but there 

appears to be no possibility of introducing this 

item on the standard certificate of birth in the 

near future. Again, marriage and fertility histories in surveys and on followback surveys of 

marriages and births must be relied on. 

For studying all of the topics mentioned 

above, longitudinal surveys would be very useful. Such surveys might, for example, begin 

with groups of young people and interyiew 

them annually to record the succession of 

events that occur: marriage, bkth, changes in 

residence, changes in jobs, etc. With the use of 

such studies we would be able to analyze the 

intricate relationships between marriage, fertility, geographic and social mobility, and a 

variety of other temporally related phenomena. 

The Relationship of Marriage and Divorce 

to Migration 

Marriage is very commonly accompanied 

by changes in residence of one or both partners. 

often these changes in residence involve moves 

over fairly long distances, and place both the 

husband and the wife in settings with which 

they may not be familiar. 

Some information on the migrations involved in marriage may be obtained from 

tabulations of the State of birth of the bride 

and groom. Complete relitice on such data 

would be unwise, however, and considerable use 

should be made of survey information to obtain 

reliable data on the previous residences of the 

bride and groom. 

The usefulness of marital status histories as 

well as fertility histories would be greatly 

enhanced by the addition of information on 

migration and social or occupational mobility. 

Changes in marital status are often accompanied 

by changes in socioeconomic status and by 

changes in residence. The collection of such 

information would make it possible to investigate a large number of hypotheses. For 

example, is divorce more or less common 

among those whose socioeconomic status is 

improving? Has divorce any relationship to 

migration born rural to urban areas? 

As mentioned previously, longitudinal 

studies would be extremely useful in analyzing 

the relationships between changes in marital 

status and migration. The general subject of 

migration is discussed in some detail in a later 

section. 

Sources of Data and Recommendations 

In the preceding discussions we have described the usefulness of six different mechanisms for obtaining information on marriage 

and divorce. They are as follows: 

1. The Marriage and Divorce Registration 

Areas, which should be completed as 

soon as possible. 

2.	 The followback surveys of marriage and 

divorce records. The results of a pretest 

5 
of a marriage followback survey in 

North Carolina in 1968 were sufficiently encouraging to justify proceeding further with the feasibility 

study as soon as possible. The feasibility of a divorce followback survey 

should also be tested. 

3.	 Household surveys (or censuses) to 

obtain current information on marital 

status and more detail on consensual 

unions. 

4.	 Household surveys to obtain personal 

histories of marriage, divorce, fertility, 

and migration status. Such surveys 

could be conducted within the framework provided by the Current Population Survey. 

5.	 Matching studies to bring together information appearing on various kinds 

of records. 

6.	 Longitudinal surveys to study the 

temporal sequence of changes in marital status, .fertility, employment, 

income, residence, and other socioeconomic variables. 

Each of these data sources has its own 

advantages and limitations. AU of them should 

be used where appropriate. However, the Subcommittee feels that the development and 

completion of the Marriage and Divorce Registration Areas and the encouragement of States 

to adopt the standard certificates of marriage 

and divorce should be given top priority at this 

time. Only these actions will provide an adequate base for the study of these phenomena in 

our society. 

FERTILITY AND FAMILY PLANNING 

Introduction following three sets of factors affecting naWith U.S. mortality at existing low levels tality: 

and with international migration not being a 

1. major factor since the 1930’s,natality has 

become the primary factor in determining 

changes in the growth rate and age-sex com2. position of the Nation’s population. Through 

the efforts of the Bureau of the Census and 

NCHS, a fairly adequate picture of U.S. natality 

is available for the present and recent past. 

3. However, more information on fertility determinants is essential both for a better understanding of the factors underlying existing 

fertility differentials within the national population as well as for an improved basis for 

predicting fertility 5, 10, or 20 years hence. 

In fact, neither the Bureau of the Census 

nor NCHS [now] provides data on any of the 

Fecundity-physiological capacity for 

childbearing, 

Reproductive norms–values relating to 

size of family and spacing between 

children, 

Family planning practices–mainly contraception, induced abortion, and 

sterilization on the side of restricting or 

postponing births and increased frequency or deliberate timing of coitus, 

artificial insemination, and other recourse to medical assistance on the side 

of augmenting birth chances. 

6 

I 
These three sets of variables are perhaps 

the most immediate determinants of marital 

fertility. They interact to determine, within a 

large margin of chance variation, the fertility 

experience of the individual woman or the 

childbearing history of the couple. The reproductive career of a couple may be usefully 

divided into two main states: the stage of rapid, 

intentional childbearing and a subsequent 

period of exposure to the risk of excess 

fertility. The operation of the above three sets 

of factors are fundamentally qualified by nuptiality: marital status determines the legitimacy 

of childbearing and exposure to the risk of 

conception with all that that portends for 

fecundity, reproductive norms, and family planning practices, while age at marriage influences 

the ages coinciding with the period of intended 

childbearing and the length of the following 

period when excess fertility is risked. The 

influence of mortality is much less because its 

level is so low. 

Three reasons may be cited for systematic 

information on the above three sets of intervening factors: 

10 A better understanding is needed of the 

origins, present status, and likely persistence of the current decline in national fertility and of present differentials in fertility among major 

social groups. Fecundity in the United 

States is generally high and relatively 

unchanging. The practice of family 

limitation is effective in most social 

groups and the long-run trend is for it 

to improve among those groups where 

its current practice is weakest. The 

relatively lower level of effectiveness of 

contraception, when practiced for 

spacing purposes, may be interpreted as 

a tolerance for a rather close spacing of 

births and could change rapidly in 

those groups characterized by effective 

family limitation if an interest in wider 

birth spacing develops, 

The most unpredictable and changeable 

component, as past rapid changes in U.S. 

fertility indicate (especially the “birth boom” 

of the late 40’s and the unexpectedly steep 

decline of the 60’s) is reproductive norms. 

Along with marriage values, what couples want 

in the way of family size and birth spacing has 

become the most strategic element in the 

determination of fertility patterns. The future 

impact of the unexpectedly steep decline of 

U.S. fertility during the last ten years, apart 

from changes in age-sex composition and in 

marriage patterns, will depend significantly on 

whether there develops a preference for either 

wider spacing of children or for smaller families. 

With fecundity differentials a secondary factor, 

the persistence of existing fertility differentials 

among major social strata will depend heavily 

on what happens to present contrasts in desired 

family size and preferred birth intervals and to 

present differences in ability to control fertility. 

2.	 If the birth rate has such a fundamental 

influence on changes of the size and 

age-sex composition of the U.S. population as well as upon changes in the sizes 

and compositions of its major subdivisions, it is obviously critical for planning purposes to be able to predict as 

well as possible the fertility trends of 

the near future and the corresponding 

differentials among the main social 

groups. Existhig natality statistics describe fairly adequately the present and 

7 
immediate past, but leave open the 

problem of predicting the future fertility of women still unmarried or in an 

early stage of family building, Of value 

as a supplement to natality statistics in 

projection work are the women’s own 

forecasts-both short run expectations 

(births to be expected in next 5 years) 

as well as anticipated ultimate additions 

to family size. With reference to specific groups, it is important to have 

accompanying data on fecundity impairments and family planning practices, since in particular groups the 

respondents are unlikely to have as 

many births as they expect or to 

restrict births to the limit anticipated. 

3.	 An increasing concern of the government, besides number of births, is the 

environment in which the children are 

raised. The couples least able to provide 

favorable environments for their children are often the couples least able to 

limit their fertility to the number of 

children desired, It has become part of 

nation~ policy to help such couples 

achieve voluntary control over their 

fertility. Official statistics on parityb provide a broad indication of the 

problem of excess fertility. However, 

direct data on the relationship of desired to attained family size provides a 

far more precise indication and documents directly the fact that large families are often not wanted. Such information is indispensable for gauging the 

magnitude of the excess fertility problem and the extent to which existing 

bParityrefersto the numberof childrenawoman 

has borne. 

local family planning services are succeeding. 

Natality Statistics 

Measures of incidence 

In a dynamic society, with rapidly changing age and sex composition, the crude birth 

rate (number of birth per 1,000 total population) is of complex meaning. More informative 

are standardized birth ratesc and birth rates by 

5-year age groups. But changes in these rates 

reflect changes in nuptiality as well as changes 

in legitimate and illegitimate fertility. More 

precise and easily interpreted are birth rates by 

age and marital status. 

For documenting current trends and differentials, the basic data are period birth rates 

which are measures that relate to limited 

periods of time, usually one year. However, 

these are affected not only by the final parities 

of contributing marriage cohorts, but the time 

patterns of childbearing. For purposes of understanding current trends and differentials as 

influenced by intervening factors and nuptiality, it is useful to have fertility measured in 

cohort terms. Cohort fertility measures are 

designed to follow the fertility of groups of 

women as they proceed through the childbearing years of life. The groups to which the 

latter rates relate are called “cohorts” and are 

identified by the year of birth of the women 

included in them. One would like to be able to 

isolate cohort trends in completed family size 

and in childspacing. But pure measures of 

fertility “quantity” and “tempo’>d (to use 

cstandardized birth rates are birth rates adjusted 

for differences in age composition of the population. 

‘<cQuantity” refers to the completed fertility of 

women.“Tempo” refersto theobservedtimepatternof 

birth rates. 
Norman Ryder’s terms)2 are hardly available 

until the cohort has completed its childbearing. 

Differences among cohorts with respect to 

age-specific birth rates may derive from nuptiality contrasts as well as from fertility differences, Easier to interpret for that reason are 

trends in duration-specific rates, preferably 

within an age at marriage classification. Another 

powerful set of cohort rates are age-parity 

specific birth rates giving a direct control over 

age, though not over interval since last birth. To 

obtain the latter, one may pass, data permitting, 

to parity-progression probabilities (i.e., proportions of women of parity X who go to the next 

parity within a stipulated duration, again preferably within an age, or age at marriage, 

classification), Strictly speaking, changes in any 

of these rates from one cohort to another are 

mirroring trends both in eventual family size 

and childspacing. However, as in the case of 

period rates, if the women contributing experience are not at the end of their childbearing, the above indices delineate only experience 

from birth (or marriage) up to the reporting 

date and do not, of course, measure later 

childbearing, This circumstance poses an awkward problem for projection work because the 

greatest interest for this purpose is the future 

fertility of women just beginning their child­

“ bearing for whom one has the least recorded 

experience. 

Data on closed birth intervals (either intervals between successive births or intervals from 

marriage to births of a specified order) appear 

to offer a pure measure of childspacing. However, subject to truncation effects, they can lead 

to difficulties of inference about trends in birth 

spacing when measured for cohorts still in the 

process of childbearing. The shorter the time 

from initial birth (or marriage) to recording 

date, the stronger is the selection for brief birth 

intervals. Hence an apparent shortening of birth 

irrtervals as one moves from earlier to later 

cohorts may reflect only an intensification of 

truncation effect. Birth intervals are more useful for analyzing the completed fertility of 

women or the fertility of women well into the 

second half of their reproductive period than 

that of women still in the period of rapid 

family-building 

Measures of cumulative fertility 

The principal measure of cumulative fertility is number of children ever born, that is, 

current parity or final parity depending on 

whether the woman has completed her childbearing or not. This measure is more meaningful 

when made age-specific, but still reflects nuptiality patterns as well as cumulative illegitimate 

and legitimate births. Less complicated to interpret are duration-specific totals of children ever 

born (with duration usually taken from first 

marriage), or as a still more refined index, 

children ever born for given durations of marriage within a classification of age at marriage. 

Even these ideal data are not pure indicators of 

eventual family size, affected as they are by 

childspacing patterns, unless, of course, the 

women contributing to the experience have 

reached the end of their reproductive period. 

Like incidence data, these measures of cumulative fertility summarize the history of the 

woman only up to the reporting date and give 

no direct indication of what will happen later in 

the reproductive period. 

Intervening Factors 

Fecundity 

The fecundity of most U.S. wives is 

adequate to permit them to have all the 

children they want. Early first marriage, the 

desire for families of moderate size, and avoid9 
ante of long intervals between intended births, 

make it possible for most wives to complete 

their desired childbearing at ages young enough : 

(usually before age 30) to escape the problem 

of fecupdity impairments. More liable to 

secondary sterility and health conditions deterring further childbearing are women who by 

virtue of late marriage, long birth intervals, or 

numerous children wanted, allow their intentional childbearing to extend well into the 2J0’s. 

With the infrequency of serious reproductive pathology during the period of rapid 

childbearing and with the childless family so 

out of fashion, the proportion of ultimately 

childless families is reaching low levels and may 

go as low as 6-8 percent.3. Among couples 

having at least one child, the proportion who 

are prevented from having all the children they 

want because of secondary sterility or deterrent 

health conditions is under 20 percent according 

to an estimate based upon 1960 data.4 

The high prevalence of normal fecundity 

during the first half of the reproductive period 

in virtually all social strata of U.S. society 

makes fecundity a negligible factor in group 

differences in fertility. An absence of fecundity 

impairments operates to increase the accuracy 

of short-run and long-run birth expectations. 

Given normal fecundity, one source of uncertainty in respondent forecasts is removed, 

though leaving other uncertainties of fertility 

intention and control. 

The effective level of fecundity in the U.S. 

is not likely to change markedly in the near 

future, [always] barring a substantial increase 

in marriage age or a trend toward longer birth 

intervals. Advances in reproductive medicine 

and increased use of these medical resources by 

the public do not necessarily lead to a simple 

effect of raising fecundity. While more fecundity impairments are being corrected, more 

health conditions are being identified as contraindications to further childbearing. 

Reproductive norms 

owing to the generally high level of 

fecundity during periods of desired childbearing, together with the effective family 

limitation of a large majority of couples, childspacing and family size norms acquire extraordinary importance. ~ntinued investigation 

of family size attitudes and values is well 

justified. Measures of desired. ideal, intended, 

and expected family sizes yield results that are 

highly correlated but far from identical There is 

a tendency for women to desire or idealize 

slightly larger families than they feel it prudent 

to have. Expected family size differs from 

intended family size whenever problems of 

fecundity or birth limitation are anticipated. 

Nso worth study are the dimensions of explicitness, spouse consensus, and stability over time. 

Spacing preferences, which may tend to be less 

explicit and less stable than family size preferences, have received much less study, a state 

of affairs hardly justified when it is considered 

that since World War II childspacing changes 

have been ascribed a larger role in the movement of period birth rates than changes in final 

parity,’ and every indication points to this 

superior significance continuing 

Given the influence and changeability of 

reproductive norms, especially those relating to 

childspacing, it is clear that population projections based wholly on birth statistics and their 

extrapolation are likely to remain unsatisfactory. The idea of incorporating respondent 

forecasts has great appeal for that reason. On 

the basis of comparisons made possible by the 

1955 and 1960 Growth of American Families 

Studies (GAF), mean births expected during the 

next 5 years have come close enough to births 

actually experienced during these 5-year intervals to win some partisans to this approach, 

Error at the level of subgroups has been 

substantial, of course, but at the aggregate level 

agreement has been fairly good as a result of the 

10

balancing effect of unanticipated subfecundity 

and failures of birth restriction. Whether this 

balance will be upset in the future by improved 

birth control or by a tendency to seek longer 

postponements of pregnancy is a matter for 

future empirical investigation. To date there is 

insufficient experience to assess properly the 

utility of respondent predictions of eventual 

family size, especially in the case of respondents 

interviewed early in their reproductive careers. 

The approach of using respondent forecasts faces a number of serious problems that 

call for further study and methodological 

innovation,b First is a technical problem arising 

because respondent forecasts relate to cohort 

fertility while the aim is to project period 

fertility. A second problem is that expectations 

‘ about final family size change over time, more 

often than not increasing as the couples age. 

Third, one is especially interested in the attitudes and predictions of the youngest cohorts 

entering child-bearing age, but the only representatives available—if the fertility survey is 

restricted to married women–are the cohort 

members marrying early whose reproductive 

intentions and expectations may not be representative of the total cohort. Still more serious, 

as the national fertility surveys have been 

designed thus far, they do not collect forecasts 

from young women not yet married. An 

important challenge to future research is the 

development and exploitation for projection 

purposes of periodic data on the childspacing 

and family size ideals and preferences of these 

young unmarried women. 

Family planning practices 

Generally favorable attitudes toward, and 

a wide practice of, family planning exist in the 

United States. The typical wife and husband do 

not try to delay their first born; unless they 

suspect subfecundity they practice contraception for spacing purposes but casually, 

thereby allowing a rather close spacing of 

desired births; thereafter through some combination of contraception, abortion, or sterilization they manage to hold family size to its 

intended limit. According to the 1960 GAF 

Study only 1’7 percent of the sample reported 

excess fertility. 7 However, this excess fertility 

falls very unevenly among social groups with 

the result that differential ability to control 

fertility is a basic factor in group differences of 

fertility. 

U.S. couples place primary reliance on 

contraception both when spacing and limiting 

family size. The 1965 National Fertility Survey 

has documented a dramatic shift in the composition .of contraceptive methods used. By 

1965, among married women under age 45 in 

the United States, 26 percent had used the 

contraceptive pill at some time and 15 percent 

were still using the pill at the time of the 

survey.8 It is obviously of great practical 

interest to be able to follow this rise of modern 

contraception and its displacement of more 

traditional methods as well as to investigate the 

impact of these newer methods on the ability of 

couples to control their fertility, especially in 

groups higherto characterized by ineffective 

contraception. It may turn out that in the 

coming decade modern contraception will exercise only rather minor effects on final family 

size because of the present effectiveness of 

family limitation among most social groups, 

although in the process it may obviate some 

induced abortion and sterilization. Perhaps the 

larger contribution of modern contraception to 

the decline of period fertility will be through its 

facilitation of longer birth intervals. 

Along with contraception and abortion, 

sterilization constitutes a basic means of family 

limitation in the U.S. By 1960, one of six wives 

at ages 35-39 in the GAF Study of that year 

reported either a remedial or a family-planning 

11 
operation, and the incidence of vasectomies had 

increased during 1955-60 period, Continuing 

information is needed on the trends and social 

differentials of both types of sterilizing operation as well as inquiry into the attitudes of 

physicians and patients toward them. 

The long periods of exposure to the risk of 

excess fertility combined with fallible contraception and only a sizable minority of couples 

resorting to sterilization would lead one to 

expect more excess fertility than is reported. 

This discrepancy can be accounted for in part 

by the resort to the practice of illegal abortion. 

Accurate statistics on the incidence of abortion 

do not currently exist, Yet without this information as it applies both to the unmarried 

and married population, our knowledge of 

fertility control in the United States ramains 

seriously incomplete. 

Relationship to Background Variables 

one may think of background factors as 

not acting directly upon fertility, but indirectly 

through intervening factors as qualified by 

nuptiality. Fertility differentials appear to be 

shrinking with two notable exceptions: religion 

and race. Fertility contrasts among religious 

groups appear to reflect primarily differences in 

desired family size and to a lesser degree factors 

such as birth spacing or effectiveness of family 

limitation. Shrinking of the differential by, 

religion “may depend, then, on a movement of 

Catholic and Protestant preferences to the 

smaller family norm of the Jewish group. In 

contrast, the fertility differential between 

whites and Negroes has depended primarily on 

an unequal success in the control of fertility, 

Especifly if persons of Southern farm background are excluded from the comparison, 

whites and Negroes within comparable socioeconomic classes appear to have fairly similar 

fertility and fertility values. For both races, as 

one goes toward the bottom of the educational 

scale, one finds less effective family limitation . 

and an increasing problem of excess fertility. In 

general, then, excluding the religious differential, differences in fertility in the U.S. are 

importantly a function of differences in excess 

fertility, reflecting unequal success in the control of fertility. It is of obvious practical 

importance to know the extent and distribution 

of this involuntary surplus natality and so far as 

possible to know [it] in advance in the form of 

respondent reports that future births are expected to exceed desired births barring unforeseen preventive action. 

One cause of less effective family limitation among the poor and poorly educated has 

been low availability of contraceptive methods 

and information. During recent years local, 

State, and federal government resources have 

increasingly been used to equalize availability 

and use of effective contraceptive methods by 

including it as part of medical care for the poor. 

It is important to know what effect these 

programs are having in reducing excess fertility 

of the poor. 

Sourcesof Data 

Health Statistics From The Center 

As the agency responsible for producing 

the Nation’s basic natdity statistics, NCHS 

publishes annual frequencies of births for “the 

Nation, states, and local areas, as well as birth 

data by a number of background characteristics 

and well-chosen sets of period and cohort 

fertility rates. However, the nature and scope of 

this information has been limited by the content of the Certificate of Live Birth. 

Questions on date of last live birth and last 

fetal death as well as education of father and 

mother were added to the 1968 revision of the 

U.S. Standard Certificate of Live Birth. A 

12

question on date of mother% first marriage was 

ttot added.9 In 1968, questions on date of last 

live birth and last fetal death were on the 

certificates of 35 States. The questions on the 

educational attainment of the father and 

mother were on the certificates of 36 States.’ 

To obtain more information on the incidence and prevalence of excess fertility, a 

question is being added to the Natahty Followback Survey to ascertain whether the most 

recent child was wanted. This may be regarded 

as a particularly important question at the 

present time because it will be useful in 

evaluating at the national level the effects of 

massive contraceptive service programs. A small 

pretest of this question in the District of 

Columbia indicated that women were willing to 

answer this question; 17 percent of the respondents said that they had not wanted 

another child at any time, and 36 percent said 

that they wanted another child, but not right 

away. The fact that 53 percent of the respondents were willing to give negative answers 

is regarded as encouraging evidence that the 

question will elicit meaningful replies. However, 

it is recognized that more methodological research will have to be done to aid in the 

interpretation of this and other information 

obtained from the Natality Followback Survey. 

It is further recommended that 2 series of 

cohort fertility rates be maintained, i.e., one for 

birth cohorts and one for marriage cohorts. As 

noted already, birth cohort fertility is influenced both by marriage rates as well as 

fertility rates, Marriage cohort fertility indicates 

the fertility trends for married women by 

duration of marriage. It is desirable to have this 

information separately for major racial groups. 

Proposed National Survey of Family Growth 

The main vehicle for collecting information about the three sets of intervening factors 

(fecundity, reproductive norms, and family 

planning practices), their interactions, and their 

relationships to natality, nuptiality, and selected background factors, is properly a federally supported series of interview surveys, 

each based on a national probability sample of 

women in the reproductive ages. The feasibility 

and value of such surveys has been decisively 

demonstrated by three previous national fertility surveys undertaken in 1955, 1960, and 

1965. These surveys have included information 

about the following topics: 

(4 

04 

(cl 

(4 

(4 

@I 

k) 

Marital history: Dates of each marriage, divorce, separation, and death of 

spouse; 

Pregnancy history: date of each birth 

and fetal death; 

Physiological ability to bear children: 

whether any obvious fecundity problems have ever been noted, whether a 

doctor was seen about them, what he 

said the trouble was, whether either 

spouse had an operation that prevents 

procreation, what the operation was, 

and why it was performed; 

Attitudes toward number of children; 

whether or not the last child was 

wanted, how many unwanted children 

were born, how many children the 

husband and wife would prefer to 

have; 

Birth expectations: how many additional children the wife expects to 

have and when she expects to have 

them; 

Attitudes toward limiting family size; 

Use of contraception: which methods 

have been used, whether they have 

been used regularly and successfully; if 

13 
no methods were used, does the 

couple expect to begin, when they will 

begin, and why have they not yet 

begun; 

(h)	 socioeconomi~ status: religion, educational attainment, color; wife’s laborforce status, occupation, and income; 

husband’s occupation and income; 

characteristics of the neighborhood in 

which the couple live. 

In future surveys, such as the proposed National 

Survey of Family Growth, it is desirable that 

sample size be at least 10,000 in order to secure 

adequate numbers of respondents in strategic 

groups (e.g., race-age-edu~ation groups). Oversampling will be needed to assure useful numbers specifically in those groups expected to 

show excess fertility or rapid changes with 

respect to marriage or fertfiity patterns, It is 

recommended that the interview surveys continue to be of the cross-sectional type, with 

interviewing confined to a limited period, 

thereby providing a design well suited to the 

production of prevalence data. The interval 

between surveys should be reduced to two years 

if possible. A desirable supplement would be a 

program of reintemiews with selected subsamples of the total sample. Two possibilities 

for this longitudinal feature are the following: 

Select a sample of young women and 

reinterview them every two years as they 

proceed through the period of rapid family 

growth. With the short recall spans involved in such interviews, it will be possible to get more accurate information on 

such topics as fetal mortality, changes in 

childbearing plans and expectations, 

changes in methods of contraception and 

success in using them, how changes in the 

couple’s economic circumstances affect 

family growth, and many other subjects. 

Select a sample of older women and 

reinterview them every two years as they 

proceed through the period of exposure to 

the risk of extess fertility. An important 

question one might investigate with the aid 

of such reinterviews is the manner in 

which couples are affected by the birth of 

unwanted children, using the wife’s attitude toward family size in the base 

interview as the independent variable. This 

makes it possible, in other words, to avoid 

the post hoc rationalization of a failure in 

family planning. 

Special Techniques 

The biggest gap in knowledge about family 

planning practices is the role of induced abortion, most of which is currently illegal. Nothing 

precise is known about the incidence or prevalence of induced abortion or variation among 

major social groups. Interview surveys have not 

produced useful incidence data, though they 

have generated worthwhile data about trends in 

attitudes towards abortion. It remains an open 

question whether the mail survey techniques 

will be able to generate more useful incidence 

data. A radically new approach may be necessary. A methodology that merits close watching is the randomized response technique 

which, though still in an early stage of testing, 

retains promise. The technique was designed to 

eliminate evasive answer bias when questions of 

a sensitive nature are asked. The procedure is 

called “randomized response” because the respondent selects a question on a probability 

basis from two or more questions without 

revealing to the interviewer which question has 

been chosen. 10 Meanwhile, efforts’ would be 

increased to require registration of all fetal 

deaths and to determine the frequency of 

abortions (and sterilizations) performed in the 

14

Nation’s hospitals through such means as the 

Nation’al Hospital Discharge Survey. One use of 

such data will be to facilitate evaluation of new 

abortion Iegklation enacted in several States. 

Special efforts should also be made to 

evaluate the effectiveness of public family 

planning services in the U.S. in terms such as 

proportion of the poor who are served, use 

effectiveness of contraception, and cost per 

unwanted birth prevented. Some useful information can be obtained from service records 

but most will probably have to come from 

household interview surveys of, e.g., low income populations, followup of women terminating pregnancy in public hospital facilities, 

and followup of families utilizing contraception in public programs. 

Recommendations 

1.	 It is recommended that a series of birth 

cohort fertility rates be maintained 

separately for major racial groups as 

well as a series of marriage cohort 

fertility rates. 

2. It remains desirable to add to the U.S. 

Standard Certificate of Live Birth a 

question on date of mother’s first 

marriage, 

3.	 The main vehicle for collecting information about the national populaMIGRATION 

Introduction rates 

ous: 

ZWeGrowing Relative Importance of Migration 

as a Component of Population Dynamics areas, 

it not 

4. 

5. 

6, 

tion’s fecundity, reproductive norms, 

and family planning practices, and the 

relation of these factors to natality, 

nuptiality, and selected background 

factors is properly a federally supported series of national interview surveys. A desirable supplement of each 

survey would be a program of reinterviews with selected subsamples of the 

total sample. 

Special efforts should be made to evaluate the effectiveness of public family 

planning services in the U.S, in terms 

such as proportion of the poor who are 

served, use effectiveness of program 

contraception, and cost per unwanted 

birth prevented. 

Efforts should be increased to require 

registration of all fetal deaths and to 

determine the frequency of abortions 

and sterilizations performed in the Nation’s hospitals through such means as 

the National Hospital Discharge Survey. 

High priority should be given to designing and testing new methodologies for 

deriving more useful data on the incidence of induced abortion, presently 

the weakest link in our knowledge of 

family planning practices in the United 

States. 

are tending to become more homogenebetween regions, between urban and rural 

and between socioeconomic strata. Were 

for internal migration, there would be 

At all levels of analysis, the migration increasing similarity in rates of growth in 

component is of growing importance in the various parts of the nation. However, equal 

study of population dynamics. Internal migra- growth rates are not the case. The phenomena 

tion is of especial importance. Death and birth of rural depopulation, westward movement, and 

15

rapid urbanization and metropolitanization are 

well known contradictions of this. However, 

these classic patterns also have changed during 

the 1960’s under the shifting tides of migration. 

some individual metropolitan areas now are 

experiencing zero or negative growth because of 

net out-migration, while others are continuing 

to grow moderately rapidlY. Internal migration 

flows now seem to be even more selective of 

place than ever before. 

The Growing Importance of Migration as a 

Component of Population Composition 

Within a nation there is a great deal of 

diversity in composition of the population. 

Some areas have a predominance of white collar 

families, while others have large masses of 

operatives and laborers. Some have large concentrations of Negroes while others are all 

white. Some are high income areas while others 

are pockets of poverty, Migration, and absence 

of migration, are major factors in creating these 

distinctive concentrations, in maintaining them, 

and in dissolving them. The mechanism is 

selective migration, or differential migration— 

the tendency for some segments of the population to be more migratory than others. For 

example, migration has transferred many thousands of persons from the depressed rural areas 

of Appalachia and the old Cotton Belt (both 

white and Negro) into northern industrial centers, where unemployment rates have been low 

and where they could enter the labor force and 

improve their lot in life. This selective migration 

has probably done as much to dissolve poverty 

as all of the anti-poverty programs combined. 

The fact that a large proportion of these masses 

were deposited in deteriorating areas of central 

cities has created, in turn, a new set of 

problems. The rapid growth of suburbs, the 

break-up of old ethnic colonies such as the 

Italian and Polish neighborhoods in cities; the 

rapid growth of the Mountain, West, and 

Southwest regions; the exodus of farmers for 

cities; the abandonment of the coal fields by 

miners displaced by automation are all examples of selective migration. 

That migration is selective has long been 

known: that modern technology tends to 

heighten its selectivity is less appreciated. Even 

less recognized is that there is comparatively 

little stability in this selectivity; it is highly 

volatile. During some decades selectivity may 

follow one pattern, whereas only a decade or so 

later it may follow the reverse pattern. Perhaps 

the only consistent principles are that the 

young and the better educated are called upon 

to make their adjustment by migration more 

often than are the old and the less well 

educated. But there are differentials by sex, 

race, ethnicity, occupation, income, marital 

status, urban-rural residence, region of residence, and other traits. The usual procedure for 

studying selectivity of migration and its impact 

upon composition is to compute the rates for 

each category of a trait or variable, and to note 

whether or not there is significant deviation 

from the average rate of migration. To the 

extent that the rates for particular categories 

deviate from the general rate, there is evidence 

of differential migration. The volume of migrants in excess or deficit of what would have 

been expected had the general migration rate 

prevailed is a measure of the impact upon 

population composition. 

Such studies of differential migration may 

be carried out from three points of view: 

(a) from the point of view of the communities 

from which the migrants depart; (b) from the 

point of view of the communities to which the 

migrants go; and (c) that of studying the composition of streams of migrants flowing between 

i6

particular pairs of places, The latter is less 

common but no less informative and important-especially in cases of massive streams. 

Relationship of Migration to Current National 

Problems 

Demographers have been accustomed to 

think of migration primarily in terms of population dynamics and its impact upon growth. 

They have tended to overlook the “human 

side” of migration. Most change of residence is 

born horn disequilibrium, and represents a 

human being or a family in search of a solution 

to a problem or set of problems. A-Uof the great 

social problems which confront the nation 

today have a migration component. 

Pot’ert~.–The incomes or employability of 

many low-income persons, can be improved by 

encouraging them to migrate elsewhere, The 

operators of submarginal farms, residents of 

small rural towns behg strangled by news 

transportation systems that speed customers to 

regional shopping and service centers, residents 

of metropolitan areas where the factories are. 

obsolescent from producing products for which 

there is declining demand, residents of communities where automation is cutting employment opportunities–all may escape poverty by 

migrating to a more promising site, 

Urban prob2ems.-The “urban crisis” of 

today has a very large migration component. 

The slums of the big city are “ports of entry” 

for low’ income migrants arriving from rural 

areas and depressed areas. They settle in the 

worst neighborhoods, the worst jobs, and are 

exploited with least protection from the law. 

Such migrants, compressed into a mass where 

they can communicate their discontent, develop 

resentment and political unrest. 

Racial integration ,–Segregation is widely 

regarded as a social problem, to be remedied by 

residential integration. This implies, of course, 

some form of residential mobility. A wider 

regional distribution of minority groups, a more 

balanced distribution between central city and 

suburbs, and a more even distribution within 

individual communities are the mechanisms by 

which integration can be achieved. 

Social maladjustment, -Mental disorders, 

family disorganization, illegitimacy, delinquency, crime, and the complete breakdown of 

“law and order” have been linked to ghetto 

IN of high mobility, where social ties are 

weak and institutional controls are ineffective 

or nonexistent. Thus, the attraction into our 

cities of the rural poor and their concentration 

into slums has led to a situation of social 

disorganization and maladjustment. 

Summary .–Like mortality and fertility, 

migration is a demographic process that operates continuously-both to preserve and to 

change existing growth and distributional patterns. Much migration represents the routine 

adjustment of persons to changes in status as 

they pass through the life cycle or “normal” 

movement required for the economy to remain 

in balance. Other migration arises fr’om fundamental imbalances and is either a result or a 

factor in many of our current natiomd problems, Migration studies may be expected to 

constitute an important challenge in the field of 

population dynamics between 1%’o and 2000. 

They will be responsible for explaining much of 

what will be happening to population growth 

and distribution. There is need for fi-esh research, with new hypotheses, new models, and 

refined multivariate analytic techniques. 

17

The Factors That Influence Migration 

Migration is a complex phenomenon, involving both an origin and a destination, It is 

best comprehended in terms of models. One of 

the most popular is the “push-pull” model, 

which claims that the factors inducing migration are a combination of negative forces of 

expulsion and positive forces of attraction. 

Another model has emphasized “intervening 

opportunities” between the place of origin and 

the destination. Everett Lee has synthesized 

these two into an overall theory that portrays 

migration as an interaction among forces of 

attraction and repulsion both at the origin and 

destination and with intervening factors that 

function to impede or discourage movement. 

AU of these models incorporate factors or 

variables which have been shown to have an 

empirical relation to migration. One important 

activity for the future is to identify and 

operationally define these variables more precisely, and to generate valid data for each. In 

this way, the models that are constructed may 

be more realistic and more capable of rigorous 

testing. 

Demographic factors 

Where birth rates are high and death rates 

are low, each oncoming generation causes the 

labor force to grow. If the communities in 

which the new labor force recruits have grown 

up are unable to provide employment, migration is the only alternative, Under conditions of 

zero population growth, the labor force recruits 

would exactly replace those retiring from the 

labor force. The “replacement ratio,” or the 

ratio of the new generation of labor force to the 

old, is a measure of the demographic pressure to 

migrate (assuming static economic conditions). 

In the past, this has been a strong force 

stimulating out-migration from rural areas, from 

the South, and fro~ other regions of high 

natural increase. As birth rates decline, the 

pressure of this demographic factor may be 

expected to diminish. 

Environmental Factors 

Particular environments are attractive because of the natural amenities they provide. 

Thus, Florida, California, and Arizona have 

attracted large numbers of migrants because of 

their mild climate, The old industrial metropolises of the East and North Central regions have 

been depleted by the massive exodus to suburbs 

and newer metropolises where there is less 

grime, pollution, and congestion. These environmental amenities seem to become more important as technology provides greater locational 

flexibility for the various types of industries 

which comprise the economy, 

Economic Factors 

AH studies of the “motives for migration” 

give top priority to the economic incentives– 

the search for employment, for better employment, for higher income, for greater security. 

Sometimes the community of origin is in a state 

of economic stagnation, as in the deforested 

areas of upper New England and the Upper 

Great Lakes areas, the Appalachian territory, 

the Midwest agricultural region, or the Old 

Plantation areas of the South. Areas where new 

industries are being established or old ones are 

growing attract migrants. The exact nature of 

this attraction–how it is sensed by the migrant, 

what varieties of workers are attracted, and over 

what distances–is as yet inadequately explored, 

Social and Psychological Factors 

Some migrants change residence because 

they are searching for better schooling for their 

18

children. others move to accompany a husband 

or father. Racial discrimination, political oppression, or religious intolerance can drive 

people from a community in search of more 

tolerable social conditions. The varied and more 

exciting social life of a large metropolis, the 

boring inactivity of the small town may both 

stimulate movement of youth. 

Other forces are more purely psychological 

or even psychiatric. Persons who are maladjusted or neurotic may tend to leave a commu ­

nity to escape the situation in which their 

anxieties have developed. Divorce can cause 

persons to wish to change residence, as can 

other uncomfortable social situations involving 

relatives, friends, or work associates. 

Still other factors may involve health or 

morals. Persons in rural areas or in areas of 

limited medical services who become seriously 

ill may migrate to areas where these services are 

more freely available. Persons who have committed crimes are highly migratory, as are those 

whose family life has been disrupted by death 

of a spouse or parent. 

Although it is recognized that all of these 

social and psychological factors affect migration, the magnitude of their impact has not 

been well measured. Often they are not dominant forces that “trigger” migration, but supplementary forces that abet movement and help 

determine the particular community chosen as 

destination. They can be fitted into migration 

models only crudely and with difficulty. 

Sources of Data 

Vital Statistics 

For the study of population dynamics, 

vital statistics can provide excellent estimates of 

net migration. By use of the simple bookkeeping equation, the natural increase component 

(births minus deaths) is subtracted from total 

intercensal increase, as measured by two censuses. The residual may be accepted as a 

reasonable estimate of net migration, provided 

the censuses are reasonably and equally accurate and vital events are registered with near 

completeness. Estimates of net migration have 

been prepared using this procedure for each 

county in the Nation for the 1950-60 decade, 

By combining these estimates, net migration 

f~res are derivable for every metropolitan 

area, every nonmetropolitan subregion, and of 

course for every State and region. Using the 

same procedure, net migration estimates for 

particular major cities (such as central cities of 

all metropolitan areas) have been prepared. 

‘III US, data are available to generate estimates of 

the net migration component of population 

growth for almost any community or major 

residence group within the United States. 

Census Data 

Thanks to a long-range and foresighted 

program of data development, the U.S. Census 

provides to American demographers the most 

detailed and most comprehensive body of migration data of any nation in the world. 

Beginning with the 1940 census, the Bureau of 

the Census has collected, as a part of each 

decennial census, data concerning the place of 

residence at some previous date (one year or 

five years) of a major cross-section of the 

population. This information has been crosstabulated with all of the array of characteristics 

collected for migrant and nonmigrant persons, 

with the result that great masses of data have 

been made available concerning the flows of 

internal migration among the various regions 

and the characteristics of these migrants, both 

with respect to the community from which 

they departed and the communities at which 

they arrived. This has been supplemented by 

19

tabulation of State-of-birth data, which provides an indirect procedure for measuring migration flows. 

Another migration estimation technique, 

the census-survival-ratio technique, permits the 

estimation of net intercensal migration by 

age-sex-color for States, regions, counties, or 

other units of area for which data are tabulated 

by these variables. 

As an integral part of the Current Population Survey, an annual measurement of migration during the preceding year has been made 

each year since 1947. This time series of 

migration yields information concerning 

changes in characteristics of migrants as well as 

changes in volume of movement. 

When all five of the procedures described 

above are exploited to their utmost, the quantity of migration information that is available 

for the United States as a whole and for each 

major part is truly impressive. There are: 

Net ..-: _.. -L,-..

rrng ratwrt: 

(a)	 The vital statistics “bookkeeping 

equation. ” 

(b)	 The census-survival-ratio estimates by 

age-sex-color, 

Gross migration: 

(c)	 The census tabulation of residence X 

years ago. 

(d) The State-of-birth tabulations, 

(e) The Current Population Survey 

annual tabulations. 

When these resources are used to reveal the 

maximum of information about the selectivity 

of migration of particular subgroups, the potential for the study of migration selectivity is 

equally favorable. Until a few years ago, full 

advantage of these opportunities could not be 

made because of the tremendous volume of 

computations required. With modern electronic 

computers this problem is resolvable. As a 

result, there is no major barrier to a burgeoning 

of research on the phenomenon of the migration component of population dynamics, using 

census data. 

National Surveys 

National censuses are able to include only 

a single (or perhaps two) questions pertaining to 

residence at some previous time, in order to 

measure migration. Considerations of cost and 

the competition of other items for a place on 

the census schedules preclude detailed data 

collection. However, national sample surveys 

can be undertaken that will provide all of the 

rich detail needed for carrying out many of the 

studies suggested above. Among such possibilities are: 

(a)	 A simple census-type question concerning residence five years ago, 

placed on special-subject surveys in 

order that migration may be related to 

all other items of data collected in 

that survey. 

(b)	 A complete migration history, from 

birth to date of interview. 

(c)	 Assessment of conditions that preceded each move. 

(d)	 Motives given by the migrant for 

making each move—both for leaving 

and for choosing a particular destination. 

(e)	 Problems encountered by the migrant 

at the destination, unmet needs, and 

the impact of the migration upon him. 

20 
(f)	 Eventual adjustment of migrants, net 

benefits of migration, and contrasts of 

migrants who have lived five, ten, or 

more years k, a community, with 

nonri-rigrantsof the same age. 

National Registers 

Many nations of the world maintain continuous population registers. Every migrating 

person is required to register his departure and 

his arrival at the new community. Some of 

these registers are administered by civil authorities and some by police or military authorities, 

In Scandinavia and The Netherlands these registers are maintained with such accuracy that 

they can be tabulated to provide highly precise 

data on migration, Although the possibilities for 

such population registers in the United States 

are quite remote, there are some registers that 

can be tabulated to yield highly useful migration data. Among these are the Social Security 

Register, policy holders of insurance companies, 

certain large registers established to make longitudinal studies (such as research projects to 

study the effect of smoking upon health), 

rationing registers, city directories, telephone 

listings, and others. As yet, these resources have 

scarcely been tapped for the study of migration. 

Migration Questions That Nead 

To Be Studied 

It is not possible in this brief document to 

provide an inventory of all the research that 

needs to be done on the migration component 

of population dynamics. It is appropriate, however, to identi$ general areas that promise to 

be especially meritorious of research attention. 

A. Explanation for the volume and characteristics of the jlow of migrants from one region to 

another, and for changes in both volume and 

characteristics. 

For example, it has been claimed 

that the northward flow of Negro migrants is much smaller in the 1960-70 

decade than in the 1950-60 decade and 

the characteristics of these migrants are 

different. Is this true? If so, what is the 

explanation? What changes of this type 

have taken place with respect to the 

flow from each region to every other 

region ? Have some of these flows become larger during the past decade? If 

SO, why? 

B. Explanation for the volume and characteristics of the jlow of migrants from one metropolitan area to another, and for changes in the 

volume and characteristics of intermetropolitan 

migration. 

By 197’0, about three-fourths of 

the population will be found living 

within standard metropolitan areas. 

During the present decade, the exodus 

of population from rural to urban areas 

is a minor part of all migration. By far 

the greatest volume of movement is 

intermetropolitan. Is this merely aimless 

movement, made for purely personal 

reasons, or does it have a deeper economic and demographic significance ? 

What are the characteristics of these 

migrants, and what forces seem to explain the movement of persons of each 

type? 

C. Full exploration of the interrelationship 

between migration and each of the other basic 

demographic processes. 

Fertility 

Mortality 

Nuptia.litye 

Socioeconomic mobility 

‘See earlier discussionof needed data on the 

relationshipof marriageanddivorceto migration. 

21 
It has been hypothesized that migrants tend to marry at an earlier age 

than nonmigrants, because they have no 

family to provide social support. It has 

been hypothesized that migrants coming 

from high fertility populations cling to 

high fertility behavior long after they 

have become identified with a low 

fertility population. It has been hypothesized that migrants are more sickly and 

more prone to mental disorders than 

nonrnigrants: one should expect higher 

death rates if this is true. It has been 

hypothesized that migration is closely 

linked to changes of socioeconomic 

status: to promotion to a new and more 

prestigious position, or fall from a 

higher to a lower position. Substantial 

increases or decreases in income are said 

to stimulate migration, as does prolonged unemployment, change of industry of employment, or attainiig a higher 

level of education. As yet these interrelationships among the components of 

population dynamics are not well understood, and we have little general theory 

to explain them. 

The 1970 census will provide much 

data, previously unavtiable, with which 

to carry out such studies. 

D. The manner in which migration occurs: 

The act of migration may take place 

in a variety of ways: 

(a)	 An entire family may move as a 

unit. 

(b)	 A single person may leave home to 

attend college and then seek employment upon graduation. 

(c)	 A person may go to a different 

community to obtsin work, and 

then send for his dependents when 

he has established himself economically. 

(d)	 A single person may go to a different community, find employment 

there, and not be followed by other 

family members. 

Little is known of the relative 

frequency of each of these patterns 

of movement, and of the conditions 

surrounding each. 

E. What is the net long-term effect of migration 

upon the migrant and his family? 

In what percentage of cases does 

migration produce a net gain? How 

many years must elapse before the gain 

outweighs the cost ? How frequently do 

migrants fail, and are forced to move on 

to another place or return to their place 

of origin? What factors are associated 

with success and with failure? What is 

the net gain or loss, both to the sending 

and the receiving community fkom migration? 

F. How intense is selective migration and how 

and why is selectivit~ changing? 

The selectivity of migration by age, 

sex, race, ethnicity, educational attainment, occupation, and other characteristics needs not only to be measured for ~ 

22 
the nation as a whole, but also needs to 

benefit from comparative studies of the 

flows between regions, from temporal 

comparisons to measure change, and 

from analytical studies seeking to explain both differences between regions 

and over time. 

Recommendations 

A, An organized effort needs to be made to 

talie advantage of available but unused migration data. 

Great masses of vital statistics and 

census data remain inadequately exploited. Massive tabulations from the 

1940, 1950, and 1960 census have yet 

to be fully analysed and interpreted. 

The vital statistics method of estimating 

net migration has not been extended to 

its limits. Special tabulations from the 

census tapes of the 1960 census can be 

made to produce even more detailed 

cross-tabulations. Many of the data are 

buried in annual reports, special publications, and computer tapes and need to 

be assembled. For example, the annual 

survey of migration conducted by the 

Census Bureau as a part of its reports on 

the labor force can be accumulated for 

several years to make more detailed 

cross tabulations than could be made 

available for any single year. 

B. Questions on migration should be made an 

integral part of the proposed National Survey of 

Family Growth. 

To the extent permitted by the 

budget and interview time, data should 

be collected concerning all of the questions raised in this section. 

C. A few “key” questions on migration should 

be made a part of national sample surveys 

sponsored by the Department of Health, Education, and Welfare and the Bureau of the Census. 

In most cases this can be a single 

question concerning place of residence 

“X” years ago (l-5 years ago). For 

example, this question should be made a 

routine part of interviews following up 

samples of births, deaths, and marriages 

and special surveys conducted for the 

anti-poverty or other special programs. 

D. A special effort needs to be made to 

assemble data for van”ables that explain migration streams and migration selectivity. 

Migration behavior will remain forever unexplained if all energies are 

devoted solely to measuring movement 

and calculating migration rates. Data 

must be assembled for variables that 

permit the testing of theories accounting for movement —this will require not 

only the variables that measure static 

conditions of individual communities 

but also changes in the social and economic conditions of these communities 

or changes in the relative position of 

these places in the total national system. 

E. Special programs need to be developed to 

process migration data by computer for analysis 

and interpretation by particular consumers. 

Much publication resource can be 

wasted in publishing hundreds or thousands of copies of very detailed tabulations which have only a single use. 

Migration tabulations tend to be 

very voluminous. Once tabulated, they 

23

are only raw data for computing rates. 

Many of the important studies that need 

to be done req&e that a special tabulation be made and recorded on computer 

tape so that one researcher may ana.lyse 

it and report the findings as a research 

study. Arrangements need to be made 

whereby this can be done for all series 

of migration data: 

Decennial censuses 

Current Population Survey 

National demographic surveys 

Other special surveys 

ROLE OF MORTALITY AND MORBIDITY IN POPULATION DYNAMICS 

Introduction 

In the dynamics of population change, 

fertility adds to population growth whereas the 

effect of mortality is to limit the size of the 

population. The impact of mortality on the 

population composition of a country may be 

seen in dramatic form when one views the 

population pyramid of a country after being 

directly involved in a major war. The loss of 

young males during a war is reflected in the 

population pyramid for years afterwards until 

the cohort becomes extinct. 

In the developing countries, the population loss through death is considerable. In these 

countries, the infant and child populations are 

the hardest hit by death. In countries where 

sizable reductions in mortality have been 

achieved, population change has resulted not 

only from the immediate effects of saving of 

lives, but from the extension of the childbearing 

period of the female population. 

In the united States, the death rate has 

now reached a relatively low level. Further 

decline may be expected, but mortality in the 

general population is no longer a significant 

component of change in population growth in 

this country. perhaps less known and less 

understood is the role of fetal mortality in 

population growth and as influencing the fertility pattern. 

In the discussion to follow, there will be 

outlined briefly the gaps in the presently 

available data on mortality needed for the 

measurement of population growth. 

Component of Population Change 

The annual depletion of the population 

due to deaths in the united States amounts to 

about 1.8 millions. This figure may be contrasted with the 3.6 million births occurring 

annually which results in a natural population 

increase of about 1.8million per year. 

The major demographic characteristics 

(i.e., age, race, and sex) of decedents are 

generally known. periodically, more detail is 

available such as marital status and occupation, 

(occupational mortality data was tabulated on 

a 100 percent basis in 1950 and on a 25 percent 

sample in 1960,) 

Natiomd life tables are published annually, 

and those for States at decennial intervals. 

These life tables have been useful in mortality 

projections for future population estimates, 

However, because of the changing mortality 

trends, research on suitable methods of mortality projection is needed. 

Generally speaking, the available mortality 

data are adequate for most purposes that 

require measures of attrition of the population. 

The data are generally satisfactory, but im24 
provement is needed in the quality of certain 

data. At the present time, the reporting of 

marital status and of age of decedent, particularly of nonwhites in the older ages, is suspect. 

Completed Fertility 

The childbearing period may terminate. 

because of biologic reasons, or it may terminate 

prematurely through death. In the years past, 

even the act of childbirth posed a serious threat 

to the life of the mother. Today, deaths from 

complications of pregnancy, childbirth and the 

puerperium number only about 1000 per year 

in the united States. Insofar as other causes of 

death are concerned, the total mortality of all 

females between the ages of 15 and 45 years 

numbers fewer than 50,000 per year. Not all of 

these women would have borne a child even if 

they had completed the childbearing period. 

Therefore, the effect of death on the female 

population in the childbearing ages is numerically fairly insignificant. 

In certain cultures, widowhood is equivalent to completed fertility. In the United States, 

remarriage of widows may, and frequently does, 

take place, According to data for 1960, it may 

be estimated that deaths of married males 15 to 

45 years create some 48,000 widows annually. 

A relatively large proportion of these widows 

will remarry. A smaller proportion will continue 

to bear children. 

The precise effect of mortality on fertility 

through termination of childbearing capabilities 

is not known. However, the number of births 

that would have otherwise occurred had it not 

been for the death of one or more of the 

marital partners must be small relative to the 

annual total. Even on an absolute basis, such a 

number cannot be very large. 

Early Pregnancy Terminations 

The present measurements of fertility are 

based upon the number of babies born alive. 

They exclude pregnancies terminated by abortions, spontaneous and induced. It has been 

estimated 1 that the frequency of induced 

abortion in the United States could be as low as 

200,000 and as high as 1.2 million per year 

depending on the assumptions made and on the 

assessment of possible biases in the various data 

series used in the estimate. The number of fetal 

deaths has been estimated Iz to be in the 

neighborhood of 500,000 per year. (How much 

overlap there is between the estimates of 

freq iency of abortions and of fetal deaths is 

not known,) Fewer than 100,000 fetal deaths 

are actually registered annually. Part of this 

discrepancy between the estimated occurrence 

and the number registered is due to the legal 

requirements of most States which do not 

require the registration of dead fetuses of less 

than 20 weeks of gestation. However, even in 

other States a large proportion of fetal deaths 

go unregistered. 

To gain a better understanding of fertility 

patterns, more needs to be known about the 

magnitude and nature of the pregnancy wastage 

problem. This problem may be viewed from 

two points of view, namely, the product of 

concepticm (dead fetus and embryo), and the 

delivery of the product (miscarriage and abortion). Very little is known of either aspect. 

Insofar as the fetus and embyro are concerned, 

an estimate of their numbers and distribution 

by sex and gestation age are needed. With 

regard to pregnant y terminations, what proportion result in miscarriages? In abortions? What 

proporti~n of induced abortions are criminal 

abortions? What proportion are induced for 

25 
medical reasons, or for family limitation purposes? 

Health and Migration 

Health, or rather ill-health, as a motivating 

factor in migration is well-recognized, but very 

little quantitative data are available on the 

‘ subject, In the yews past when tuberculosis was 

a major public health problem, mortality data 

showed heavy migration of those with tuberculosis to States like Arizona, Colorado and New 

Mexico. With the large decline in tuberculosis 

mortality, population movement for treatment 

of specific diseases is not as clear. However, 

there still appears to be a flow of population to 

Florida, California and Arizona for retirement 

purposes. Part of this migratory movement 

must be health related. 

Health Consequences of Population Change 

The nature of health problems and services 

will depend to a large extent on the characteristics of the population of an area, For example, 

in a young population, the major problems are 

likely to be obstetrical and pediatric in nature. 

In a community of elderly people, geriatric 

cases will predominate coupled with demands 

The Subcommittee has reviewed what 

seem to be the principal needs for improvement 

in the statistics on population dynamics for this 

country. It has offered proposals as to how 

these needs might best be met. Starting with the 

data that are available, the Subcommittee has 

sought to indicate ways of improving existing 

data sources and to recommend certain new 

data sources. 

The main finding of the Subcommittee’s 

review is that, although there are many sources 

26 

for nursing services. In a young community, th: 

mortality will be low and in an aging population 

the mortality will tend to be high, These an: 

some of the consequences of populatiosl 

change. 

Recommendations 

1.	 Pregnancy wastage is a problem of’ 

considerable, but unknown, magnitude 

which may significantly affect fertility 

patterns. Research is needed to develop 

methods to determine the magnitude of 

this problem. 

2.	 Through the use of hospital data, the 

present level of miscarriages and abor- I 

tions should be estimated, For induced 

abortions, an attempt should be made 

to estimate the number of criminal 

abortions. 

3. Because of incomt)leteness of fetal L 

death registration, relatively little is 

known about the distribution of fetal 

deaths by period of ~estation. ~tu{li(i.+ 

of cohorts of pregnant womn SIIOU1(I 

be undertaken so that pre:nan(.) out. 

comes and the age and sex dis(ril)u[ ion 

of fetal deaths can be dett>rmint,(l, 

of data in population dynamics in the United 

States, there is no continuing data-collection 

mechanism that has the measurement of family 

growth as its principal concern. The Census 

data, the general-purpose demographic surveys 

conducted by the government, and the data 

developed from records of birth, death, marriage, and divorce have continued to improve, 

and the Subcommittee has devoted much attention to ways in which these resources should be 

further exploited. Nonetheless, these sources, 
designed as they are formany uses, do not lend 

themselves to the intensive study of a number 

of topics of special concern. This is especially 

true with regard to the statistics which are 

needed in order to understand what is happening to the birth rate in the United States. 

It is past time for the establishment by the 

Federal Government of a National Survey of 

Family Growth, repeated at regular intervals, to 

provide information on fecundity, reproductive 

norms, and family planning practices, their 

interrelations, and their relations to natality, 

nuptiality, and selected background factors. 

The importance of the topics to be covered ‘in 

such a survey is indicated by the broad and 

burgeoning Federal emphasis on population and 

family planning, and by the dominating role 

which fluctuating birth rates have played in the 

population growth in the United States in 

recent years. In this connection the Subcommittee concurs emphatically in the recent recommendation by the President’s Committee on 

Population and Family Planning (November 

1968): 

That the National Center for Health Statistics be given funds to establish a continuing survey of family growth in the United 

States in order to determine trends in 

childbearing patterns and factors affecting 

the American birth rate. 

Such a survey would represent a vital step 

forward in achieving the three-fold objectives 

set forth in the chapter on Fertility and Family 

Planning, which are: To understand the current 

decline in American fertility and of present 

differentials in the fertility of major social 

groups, to anticipate the course of these trends 

in the near future, and to assess the success of 

Federal programs aimed at aiding couples who 

wish to achieve voluntary control of their 

family size. 

The feasibility and usefulness of a continuing survey of family growth have been amply 

demonstrated by several private studies of a 

similar nature which, however, lack the scale, 

frequency, and continuity that are needed. The 

development and maintenance of frequent surveys on this topic are clearly a matter of 

Federal interest and, given the unique Federal 

competence in the conduct of repetitive, largescale statistical programs, this is clearly a 

Federal responsibility. 

Although the birth rate is the main dynamic factor affecting the size of the Nation’s 

population, migration within the country is 

mainly responsible for the changing concentration of population in geographic areas. In the 

concern for population and family planning, it 

is easy to overlook this fact, and to underestimate the degree to which the Nation’s population problems are local problems resulting from 

imbalances in the distribution of population in 

relation to the distribution of jobs, housing, 

transportation, public facilities and the like. 

The movements of people from the South to 

the North and West, from farms to towns and 

cities, from nonmetropolitan to metropolis an 

areas, and from cities to suburbs, have been 

detailed in an abundance of excellent statistics 

from the Bureau of the Census. However, the 

understanding of this movement, the conditions 

giving rise to it, and the problems that it poses 

for the sending as well as the receiving communities, presupposes an investment in compilation and analysis of the data which have been 

collected and in some additional data collection 

which is not yet in sight, and which ought to be 

made. 

The Subcommittee’s recommendations include other proposals for the establishment of 

new sources of demographic statistics, such as 

27 
sample surveys of marriages and divorces to 

supplement the information on the marriage 

and divorce certificates. In addition, the fkbcommittee has made recommendations for continued efforts to extend and improve the 

existing demographic statistical systems, for 

example, the further extension of the Marriage 

and Divorce Registration Areas and the registration of fetal deaths. Other recommendations are 

for greater utilization of existing data-collection 

mechanisms for poptilation dynamics uses, such 

as the inclusion on a regular basis of such items 

as questions on migration and on marriage and 

divorce, and utilization of the Hospital Discharge Survey to collect information on abortions. There are also recommendations for 

greater exploitation of basic data already collected, for example, the preparation of tabulations relating the size and composition of 

migration streams to changing characteristics of 

the communities involved, and the preparation 

of marriage- and birth-cohort fertility data for 

major racial groups. Still other recommendations call for the pursuit of methodological 

innovations, such as the use of randomized 

response techniques in the collection of data on 

abortion or other sensitive matters. 

The foregoing recommendations have been 

concerned with the substance of the information which is produced. There are, in addition, 

several issues involving the form in which the 

information is made available. The usefulness of 

all the efforts being made in this area, as well as 

those which have been recommended, depends 

on how readily the results can be utilized to 

produce knowledge, It appears to the Subcommittee that in certain important respects the 

output of the statistical agencies needs improvement when seen in this light. The agencies have 

shown themselves capable of producing, and the 

users have shown themselves capable of assimilating a far more varie~ output than is repre~ 

sented by the statistics that are regularly published. It is the sense of the Subcommittee that 

the agencies should push forward in two ways: 

(1) to give increasing emphasis to analytical uses 

in designing their statistical output, and (2) to 

give increasing emphasis to the production of 

public-use samples (that is, basic data tapes for 

use outside the agencies) and other data tapes 

which provide for the exercise of maximum 

flexibility, speed, and ingenuity. by the analyst 

while at the same time preserving the confidentiality of individual records. 

Improvements in the usefulness of statistics for analytical purposes require improvements in the ways in which the data are handled 

and presented. This implies, at a minimum, the 

production of more satisfactory denominators 

for calculating annual birth, marriage, and 

divorce rates by characteristics of the population. ‘I%is could be accomplished by the routine 

preparation of averages based on several surveys 

rather than limiting the tabulations to a single 

survey. 

On another level, the Subcommittee believes the statistical agencies should devote 

more effort to the production of analytical 

statistics such as those yielded by various kinds 

of models. Such analytical statistics are commonplace in some areas of official “demographic 

statistics; they are in only preliminary developmental stages in others. For example, the 

National Center for Health Statistics and its 

predecessor agencies have published annual life 

tables as a routine matter for the past three 

decades. Nowadays nobody would consider it 

adequate if the agency responsible were simply 

to publish death rates, let alone tabulations of 

death records. The regular publication of life 

tables has had the result that life-table measures 

are now widely understood and universally used 

as a standard means for expressing the force of 

mortality. 

28 
Although an abstract and sophisticated 

analytical model now provides the common 

terms for the communication of information on 

mortality, this is not true for some of the other 

topics covered in population dynamics. For 

these topics, the agencies should be encouraged 

to give more systematic effort in directions 

where they have already shown initiative. For 

exaniple, the marriage model which Donald 

Akers developed at the Bureau of the Census 

can serve as a potent tool for analyzing and 

expressing changes in marriage rates, proportions marrying, age at marriage, annual number 

of marriages, and the relationships of these to 

the changing population of marriageable age.13 

In addition, a Monte carlo demographic simulation model (an interaction model) is being 

developed by the Research Triangle Institute 

and the University of North Carolina under the 

auspices of the National Center for Health 

Statistics. Efforts such ~as these should be 

multiplied, and the results should be incorporated in the regular publication program of the 

agencies as early as possible. 

The general point in what the Subcommittee is asking is that the agencies devote more 

attention to presenting the information they 

collect in maximally usable form. By virtue of 

the potentiality of their electronic equipment 

and the knowledge of their staffs, these agencies 

are in a position to supply information that will 

contribute to demographic knowledge much 

more readily than at present, The users of 

statistics need, and are ready to receive, data 

that are processed to a more advanced state 

than is now common. Furthermore, experience 

has shown that the demand for more refined 

statistics will expand when such statistics are 

produced on a regular basis. 

The Subcommittee’s view of the role of 

the statistical agencies extends also to the 

substantive analysis of the data which they 

publish. The talents of the agency staffs would 

justify, and the public understanding of population dynamics would benefit from, more activity of this kind. Their closeness to the data puts 

these professionals in a unique position to 

produce informed descriptions and analyses of 

what is taking place in the population. The 

Subcommittee does not advocate interpretation 

on controversial questions or issues of policy. 

However, the sensitivity of certain staffs to the 

data needs and their interest in improving the 

data depend to a significant degree on the 

extent to which the agency staffs use the data. 

Furthermore, the development of the recommended analytical statistics presupposes a level 

of systematic in-house research not as yet 

achieved, or likely to be achieved unless more 

staff time is freed from the preoccupation with 

day-to-day problems of data production. Systematic agency support for substantive staff 

research and analysis will benefit the data, the 

ability of the agencies to attract and retain 

talent, and public knowledge in the population 

dynamics field. As an example of such analytical activities, the National Center for Health 

Statistics and the Bureau of the Census should 

be encouraged to cooperate in the preparation 

of a decennial report on population dynamics. 

At the same time that the Subcommittee 

encourages greater analytical activity by the 

agencies, it also sees ways in which the agencies 

can do more to facilitate analysis by others. h 

example is the release of public-use samples and 

of summary tapes. The Bureau of the Census 

pioneered the development of public-use samples with its 1/1,000 sample of the 1960 Census 

results. ‘I%is resource has been widely used. The 

tapes (or cards) were processed in advance of 

distribution so as to avoid any possibility of 

identification of individual persons, thus observing the confidentialityy provisions governing the 

collection of the data. With appropriate safe29 
guards, the Bureau of ‘the Census has made 

tapes of certain current surveys available to 

selected Federal agencies for theh- research. The 

release of information in this form permits 

maximum flexibility to the researcher and 

greatly reduces the time required to conduct 

research than is the case with special tabulations 

obtained on order from the statistical agencies. 

The principle of public-use samples should be 

extended to other key surveys including the 

proposed National Survey of Family Growth to 

which the Subcommittee has given the highest 

priority, and to the vital statistics. A public-use 

sample of birth records should be released for 

each year. In doing this, the agencies will have 

to develop tape formatting and documentation 

of a kind that has not been required for their 

internal use of the tapes, but is necessary in 

order to facilitate the use of the date in this 

form by outsiders, 

The Bureau of the Census is preparing to 

supply orders for a wide variety of summary 

tapes from the 1970 Census. These are tapes 

which show the statistics in standard tabulation 

detail for areas that are too small and too 

numerous for publication of the full detail in 

the regular census volumes. The provision of 

statistics in this form permits the user to 

recombine areas in nearly any form he desires. 

A large demand for such tapes from the census 

is anticipated. The Subcommittee urges the 

National Center for Health Statistics to explore 

the desirability and feasibility of distributing 

the vital statistics on summary tapes. These 

tapes would have a number of uses, such as 

measurement of geographical concentrations of 

high order births, illegitimate births, etc. Since 

many uses of the information in summary tape 

form are for local areas, consideration should be 

given to presenting such data for 100-p.ercent 

samples of births, marriages, and divorces in 

order to improve the reliabilityof the data at 

the local level. However, the presentation of 

100-percent” data should not be done at the risk 

of delay in publication of the vital statistics. 

Indeed, a concerted effort should be made to 

improve the timeliness of both reporting and 

publication. 

The implementation of the recommendations presented in this report requires further 

improvement of coordination between the agencies involved. To this end, the Subcommittee 

recommends to the Directors of the National 

Center for Health Statistics and the Bureau of 

the Census that they consider expanding the 

functions of the Joint Census-NCHS Committee 

on Fertility to include all of population dynamics and that they consider having this 

committee report to the office of the Director 

of each agency. Substantial agenda for such a 

committee are implicit in the recommendations 

in this report. AII early item of business might 

be the decennial report on population dynamics 

mentioned above. 

The Subcommittee commends to the agencies the great potential for coordination and 

stimulation of demographic research within the 

Government that is represented by the program 

of the new Center for Population Research of 

the National Institute for Child Health and 

Human Development. The establishment of the 

Center, and its announced program, augur most 

favorably for the future development of the 

field of population dynamics in the Federal 

Government, given the necessary cooperation. 

The Subcommittee is aware of the current 

“invasion of privacy’9 issue as it related to 

Federal statistical activity. It recognizes the 

legitimacy of the public concern over electronic 

eavesdropping, misuse of credit information, 

and similar real invasions of privacy where 

individual information, supplied without knowledge or supplied innocently for another purpose, has been misused to the detriment of the 

30 
individual. However, such concerns are misdirected when they are directed to the Bureau of 

the Census and the National Center for Health 

Statistics, whose programs have been discussed 

in this report. These agencies collect information from the public under an absolute bond of 

confidentiality, for well-established public purposes. The information can be used for statistical purposes only, and the information on 

individuals cannot be seen by any person other 

than a sworn agent of the organization which 

collected it, under strict legal penalties for 

violation. The Subcommittee knows of no case 

in which this confidentiality has been broken 

by either the Bureau of the Census or the 

National Center for Health Statistics, and it has 

confidence in the intent and ability of these 

agencies to maintain this principle. 

The statistics which these agencies produce, and those additional statistics which have 

been recommended, are essential to the needs 

of our society. Indeed, this entixe report is the 

Subcommittee’s testimony to its view that a 

substantial public interest is at stake in the 

improvement and expansion of the programs 

under discussion. 

REFERENLcS 

1. Unpublished Ph.D. dissertation.University of 

Michigan,	 1965. 

2, Ryder, N. B.: The emergence of a modern fertfiity 

pattern; United States. Behrman, S. J., Corsa, L., and 

Freedman, R., (eds,) FertiliW and FamilyPLznning,A 

World View Ann Arbor, University of Michigan Press, 

1969. pp. 99-123. 

3. Whelpton, P. K., Campbell, A. A., and Patterson, J. 

E,: Fertility and FamilyP.hnningin the UnitedState~ 

Princeton. Princeton University Press, 1966. pp. 

162-163. 

4. Ibid., pp. 166-168. 

5. Kiser, C, V., Grabill, W. H., and Campbell, A. A.: 

i%endsand Partitions in Fertili@ in the UnitedStates 

Cambridge, Harvard ‘University Press, 1968. pp. 

255-284. 

6. Ryder, N. B., and Westoff, C. F.: The trend of 

expected parity in the United States, 1955, 1960, 1965. 

Popw!Index 30(2): 153-168,Apr. 1964. 

7. Whelpton, P. K., et al: op. cit.,p. 225. 

* U. S. GOVERNMENT PRINTINP flFFICE -1970 – ase-~a p. 0. == 

8. Ryder, N. B., and Westoff, C. F.: Use of oral 

contraception in the United States, 1965. Science 153: 

1203, Sept. 9, 1966. 

9. National Center for Health Statistics: The 1968 

Revision of the Standard Certificates. Vitaland Health 

Statistics PHS Pub. No. 1000–Series 4–No. 8. Public 

Health Service, Washington, U.S. Government Printing 

Office, June 1968. pp. 10-1 L 

10. Abernathy, J. R., Greenberg, B, G., and Horvitz, D. 

G.: Preliminary Estimates of Induced Abortion in North 

Carolina. paper presented at the annual meeting of the 

Population Association of America, Atlantic City, Apr. 

11, 1969. 

11. Calderone, M. S., cd,: Abortion in the United 

States New York. Paul B. Hoeber, Inc., 1958. p, 180. 

12. National Office of Vital Statistics: Major problems 

in fetal mortality, by J. Yerushalmy and J. Bierman. 

VitalStatistics–SpectilReports. Vol. 33, No. 13. Public 

Health Service. Washington, D.C,, 1952. 

13. Akers, D. S.: On Measuring the Marriage Squeeze. 

DemographyIV (2): 907-924,1967. 

31

OUTLINE OF REPORT SERIES FOR VITAL AND HEALTH STATISTICS 

Public Health Service Publication No. 1000 

Series 1. 

Sevies 2. 

Series 3. 

Series 4. 

SeVies 10. 

Sevies 11. 

SeVies 12. 

Series 13. 

Series 14. 

Se7ies 20. 

Se7ies 21. 

Series 22. 

Pvograrns artd collection proceduves.— Reports which describe the general programs of the National 

Center for Health Statistics and its offices and divisions, data collection methods used, definitions, 

and other material necessary for understanding the data. 

Data evaluation and methods vesearch. —Studies of new statistical methodology including: experimental tests of new survey methods, studies of vital statistics collection methods, new analytical 

techniques, objective evaluations of reliability of collected data, contributions to statistical theory. 

Analytical studies. — Reports presenting analytical or interpretive studies based on vital and health 

statistics, carrying the analysis further than the expository types of reports in the other series. 

Documents and committee reports. — Final reports of major committees concerned with vital and 

health statistics, and documents such as recommended model vital registration laws and revised birth 

and death certificates. 

Data jkom the Health Interview Survey. —Statistics on illness, accidental injuries, disability, use of 

hospital, medical, dental, and other ser’vices, and other health-related topics, based on data collected 

in a continuing national household interview survey. 

Data from the Health Examination Survey. — Data from direct examination, testing, and measurement of national samples of the population provide the basis for two types of reports: (1) estimates 

of the medically defined prevalence of specific diseases in the United States and the distributions of 

the population with reqpect to physical, physiological, and psychological characteristics; and (2) 

analysis of relationships among the various measurements without reference to an explicit finite 

universe of persons. 

Data f~om the Institutional Population Surveys. —Statistics relating to the health characteristics of 

persons in institutions, and on medical, nursing, and personal care received, based on national 

samples of establishments providing these services and samples of the residents or patients. 

Data from the Hospital Discharge survey. —Statistics relating to discharged patients in short-stay 

hospitals, based on a sample of patient records in a “national sanlPle of hospitals. 

DOta on health resources: manpowev and facilities. — Statistics on the numbers, geographic distribution, and characteristics of health resources including physicians, dentists, nurses, other health 

manpower occupations, hospitals, nursin$z homes, and outpatient and other inpatient facilities. 

Data on mortality. —Various statistics on mortality other than as included in annual or monthly 

reports —special analyses by cause of death, age, and other demographic variables, also geographic 

and time series analyses. 

Data on natality, mavriage, and divorce. —Various statistics on natality, marriage, and divorce other 

than as included in annual or monthly reports— special analyses by demographic variables, also 

geographic and time series analyses, studies of fertility. 

Data from the National Natality and Mortality %’veys. —statistics on characteristics of births and 

deaths not available from the vital records, based on sample surveys stemming from these records, 

including such topics as mortality by socioeconomic class, medical experience in the last year of 

life, characteristics of pregnancy, Wc. 

For a list of titles of reports published in these series, write to: Office of Information 

National Center for Health Statistics


U.S. Public Health Service


Rockville, Md. 20852