CPS BRIDGE TEAM TECHNICAL REPORT 3

Effect of Design Differences Between the

Parallel Survey and the New CPS

Prepared by

Donna L. Kostanich

Lawrence S. Cahoon

For the CPS Bridge Team

March 4, 1994
2

Executive Summary of

CPS BRIDGE TEAM TECHNICAL REPORT 3

Effects of Design Differences Between the

Parallel Survey and the Redesigned Current Population Survey

March 4, 1994

The official monthly labor force estimates from January 1994 onward will be based on data from

a comprehensively redesigned Current Population Survey (CPS). The redesign incorporates

changes in the basic questionnaire and collection methods. In addition, these estimates will be

constructed using the 1990-census-based population controls rather than 1980-census-based

population controls.

In order to gauge the effects of the CPS redesign on published estimates, a Parallel Survey (PS),

intended to provide annual average laborforce estimates, was conducted from July 1992 to

December 1993. The PS used a separate monthly sample of households approximately one-fifth

the size of the regular CPS sample. 

Annual average estimates from the PS were compared to the CPS for 1993. These comparisons

provide estimates of the overall effect of switching to the new questionnaire and collection

methods. This study showed an expected .45 (or rounded to .5) percentage point increase in the

unemployment rate. (For a general discussion of these results, see the February 1994 issue of

Employment and Earnings; for a more detailed discussion, see Polivka 1994). These results do

not provide an estimate of the effect of switching from the old CPS to the redesigned CPS,

because not all design differences were accounted for. We have known for some time that at

least one design difference had a measurable effect on the estimated unemployment rate. That

is, the change in the population controls resulted in an additional .10 percentage point increase in

the unemployment rate; implying a total effect of .55 (or rounded to .6) on the unemployment

rate. (See table D, The Employment Situation: January 1994.) With the completion of the PS, it

became possible to estimate the effects of the design differences.

To better understand the effect of design differences between PS in 1993 and CPS in 1994, the

CPS Bridge Team has obtained estimates of several design differences. Three design

differences, present in January 1994, which we have examined are: 1) The redesigned CPS

uses 1990-census-based population controls rather than the 1980-census-based controls; 2) The

PS used fewer post-stratification controls than the CPS due to smaller sample sizes and different

sample designs; and 3) About 18 percent of the PS sample was interviewed at centralized

telephone facilities, as compared to 12.5 percent in the redesigned CPS. 
3

Accounting for these design differences, the expected increase in the January 1994

unemployment rate is marginally greater--.48 percentage point. This estimate, as well as each of

the individual effects given below, are subject to sampling variance; thus, the actual effects will

differ from the estimated effects. The specific estimated effects are:

• An increase of .10 percentage point on 1993 CPS due to the change to 1990-

census-based population controls. (The actual increase in the PS was .12. This 

is a less accurate measure due to the smaller PS sample size.)

• An increase of .01 percentage point due to fewer post-stratification controls.

• A decrease of .08 percentage point due to less centralized interviewing in the new

CPS.

Except for the .01 percentage point increase due to fewer post-stratification controls, the overall

effects and the other individual effects are believed to be statistically significant; although the

centralization effect was marginally significant.

After January 1994, two additional changes will occur. The composite estimator will be

introduced in early 1994, and the proportion of centralized interviewing will equal the

proportion present in the PS by June 1994. Increasing centralized interviewing removes the

decrease of .08 percentage point present in January to give an expected increase of .56

percentage point on the unemployment rate. The effect of the composite estimator is much less

certain. As the composite estimator is introduced, the expectation is that the unemployment rate

may drop by as much as .06 percentage point, or it may increase by .02 percentage point. 

Applying the 1993 CPS seasonal adjustment factors to the time series for the PS and the CPS

showed no additional effects. This is primarily due to use of the same adjustment factors on

both surveys. However, it will take some time before we know the seasonal pattern for the new

CPS.

Additionally, the switch to using 1990-based population controls will increase the variance on

many estimates. Overall the increases are expected to be small.

Our best estimate of the combined redesign effects on the annual average unemployment rate is

an increase of .56 percentage point. This is before compositing or seasonal adjustment. It will

be awhile before we can determine a more precise estimate of the effect of compositing or

seasonal adjustment.
4

Acknowledgments

The members of the CPS Bridge Team were: Chester E. Bowie, Shail J. Butani, Lawrence S.

Cahoon, Cathryn S. Dippo, Robert E. Fay, Donna L. Kostanich, Elizabeth A. Martin,

Stephen M. Miller, Anne E. Polivka, N. Clyde Tucker. Other participants in the work of the

team were: Katharine G. Abraham, John E. Bregger, Mike Couper, Thomas J. Plewes, and

Jennifer M. Rothgeb. Outside consultants included Wayne A. Fuller and Robert M. Groves. 

This report was prepared by Lawrence S. Cahoon and Donna L. Kostanich. Additional

assistance was provided by Randall J. Parmer, Harland H. Shoemaker, Yves R. Thibaudeau,

Jenny Thompson, Michele A. Roberts, Ronald R. Tucker, Janice Lent, and Kenneth W.

Robertson. Special thanks is extended to Robert E. Fay and Athar Malik, who contributed

significantly to this report.
5

Introduction

The official monthly labor force estimates from January 1994 onward will be based on data from

a comprehensively redesigned Current Population Survey (CPS). The redesign incorporates

changes in the basic questionnaire and collection methodology. In addition, these estimates will

be constructed using the 1990-census-based population controls rather than 1980-census-based

controls.

In order to gauge the effects of the CPS redesign on published estimates, a Parallel Survey (PS),

intended to provide annual average laborforce estimates, was conducted from July 1992 to

December 1993. The PS used a separate monthly sample of households approximately one-fifth

the size of the regular CPS sample.

Annual average estimates for 1993 from the PS have been compared to those from the CPS to

give our best overall understanding about the effects of questionnaire redesign and change in

collection procedures (Polivka 1994). The redesign analysis is limited to the extent that

differences in centralized interviewing and the number of post-stratification controls used in the

estimation could be contributing to the overall findings. Thus, these comparisons do not provide

estimates of the effect of switching from the old CPS to the new CPS, because these two design

differences are not accounted for. Furthermore, we still need to account for the effects of

switching to 1990 census population controls, not using the composite estimator in January

1994, and using the old CPS seasonal adjustment factors.

To better understand the effect of design differences between the PS in 1993 and the CPS in

1994, this report presents information on five design differences--1990 census population

controls, the number of post-stratification controls, the amount of centralized interviewing,

composite estimation, and seasonal adjustment. Switching to 1990 census population controls

also has an effect on the reliability of estimates. Information on how the variances are expected

to change is included in this report as well.

This report, which is the product of joint work between the Bureau of Labor Statistics and the

Bureau of the Census, is laid out as follows. The Background section provides an introduction

to the Parallel Survey, as well as a discussion of the differences between the PS and the

redesigned CPS. The Results section gives additional information on how laborforce

characteristics are affected by the design differences. General conclusions about the effect of

these design differences are given in the Summary section.

Background
6

Redesign of the Current Population Survey

The CPS is a national survey of approximately 60,000 households which provides a monthly

picture of the nation's laborforce characteristics, including employment, unemployment, and

those not in the laborforce. The CPS began in 1940, and the questionnaire has remained

essentially unchanged since the last redesign in 1967. The current redesign was undertaken to

reflect changes which have taken place in the workforce and structure of American society, as

well as to take advantage of changes and improvements in survey methods, such as computerassisted data collection and questionnaire methods based on the theories of cognitive

psychology. Further discussion of the questionnaire and mode of collection changes

incorporated into the CPS in January 1994 can be found in Bregger and Dippo (1993).

Although computer-assisted interviewing was used for all interviews in January 1994, the mix

between centralized and decentralized interviewing will change during 1994. In January 1994,

the amount of centralized interviewing increased to 12.5 percent from a previous level of 9

percent. During 1994, the amount of centralized interviewing will increase to 18 percent, the

amount present in the Parallel Survey (PS).

In addition to the changes in data collection procedures incorporated into the CPS in January

1994, changes in estimation procedures have also taken place. In January 1994, the CPS began

using post-stratification controls based on the 1990-census population adjusted for undercount. 

The composite estimator was not used. The seasonal adjustment factors applied to the January

1994 CPS estimates and to be applied to future months have been computed from the old CPS. 

Although estimates from the new CPS will be used in the mid-1994 revision of seasonal factors,

it will be awhile before we can determine the seasonal patterns for the new CPS.

In order to better understand the effects of the CPS redesign upon published estimates, the

Parallel Survey was conducted from July 1992 to December 1993 using a monthly sample of

approximately 12,000 households.

Design Differences Between CPS and PS

The design of the PS was basically that of the National Crime Victimization Survey. Like the

CPS, the PS was a multistage probability sample in which large metropolitan areas are selected

with certainty, and smaller primary sampling units are selected with probability proportional to

size within strata. For the PS, strata were defined within region, rather than State, as in the CPS.

 Moreover, the CPS has a much larger sample,-- 60,000 households monthly, as compared to

12,000 in the PS. Sampled addresses in the CPS are interviewed for 4 consecutive months, are

out of sample for 8 months, and are interviewed again for 4 additional months. Consequently, in

any given month the sample is partitioned into 8 rotation groups, with one being interviewed for
7

the first time, one for the second time, etc. (See Miller 1994). The PS used this same sample

rotation pattern; however, due to the amount of time needed to phase this rotation pattern in, the

PS did not completely achieve the CPS rotation pattern until September 1993. Consequently,

the effect of the PS rotation pattern could not be measured.

The estimation procedure for the PS was very similar to that used for the CPS, with the major

difference being the number of post-stratification controls used. Post-stratification is used to

benchmark survey data to population estimates and is accomplished by a 3-step iterative rake to:

 1) State, 2) national Hispanic ethnicity by sex and age, and 3) national race by sex and age. In

the CPS, the national steps use about 600 population estimates. For the PS, the control to State

population estimates was excluded and the number of national age/sex/race ethnicity population

controls was reduced to about 559. This difference is a direct consequence of the PS's smaller

sample size and the fact that the PS did not use State strata. (The PS was never designed to

produce State estimates like the CPS.) The population estimates used as controls in the poststratification procedure are based on the Decennial Census and adjusted forward to reflect births,

deaths, immigration, and emigration. In January 1994, the CPS switched to controls based on

the 1990 census adjusted for undercount. Previously these controls were based on the 1980

census. 

Another design difference between the PS and the CPS is the extent to which centralized

interviewing was used. Approximately 18 percent of the PS sample was interviewed from a

centralized facility, as compared to 9 percent for CPS during the same time frame. Statistical

evidence about centralized interviewing effects was only recently obtained, even though

centralized computer-assisted telephone interviewing (CATI) has been used in the CPS since

January 1989. A computerized version of the then current, now old, questionnaire was

developed and administered by a staff of telephone interviewers working out of a centralized

facility in Hagerstown, Maryland. In order to minimize any potential effects on published CPS

estimates, the percent of sample cases interviewed from CATI was purposely kept small. Over a

period of 5 years, the percent of the CPS sample interviewed from CATI gradually increased to

the 9 percent level used in the 1993 CPS. 

In order to evaluate the effects of using CATI on CPS estimates, sample housing units were

randomly assigned to be or not to be CATI eligible. Findings based on CPS data collected

between January 1991 through December 1992 showed that CATI produced an unemployment

rate 0.8 percentage point higher for the test group eligible for CATI than the control group not

eligible for CATI. (Shoemaker 1993). The old paper and pencil questionnaire was just not

administered from a centralized location, it was converted to and administered via a

computerized version, and the wording of question 19 had been modified1

. Thus, it was not

possible to distinguish whether this difference was due to centralization, computerization, or a

slightly modified questionnaire. 

Cognizant of this CATI effect on CPS estimates, the PS was also designed to facilitate an

evaluation of centralized interviewing. (For a discussion of these results, see Kostanich (1994)).

 The sample sizes for the centralization test in the PS were extremely small. The test group had
8

only 5,500 housing units per month, and the control group had only 600 housing units per

month. These small sample sizes caused the variability to be too large to draw any conclusions

until the test was complete in December 1993.

More details and background on these design differences are given in Miller (1994). The

following table highlights these differences.

Table 1. Design features of CPS and PS

 

 CPS PS

Sample design:

 Sample size (occupied housing units) 58,900 12,000

 Primary strata within State within region

Post-stratification:

 Source of controls 1980 census* 1980 census

 Number of controls 600 National

51 States

559 National

No States

Collection procedures:

 Percent noncentralized 91 percent (paper and pencil)* 82 percent (computer)

 Percent centralized 9 percent (computer)* 18 percent (computer)

*Changed for CPS beginning in January 1994

1 See Rothgeb (1994) for a more detailed discussion about question 19 and possible influences of computer

assisted interviewing and centralization. 

Results

Section I gives more details on how each of these five design differences affect major laborforce

estimates. Generally, results are presented for unemployment rates, employment-to-population

ratios, and civilian laborforce participation rates for selected demographic groups. First, the
9

effects due to the two differences in the post-stratification procedure are discussed. How the

source of the post-stratification controls (1980 vs. 1990-census-based population controls)

affects laborforce estimates is given in part A, while the effect due to the number of poststratification controls used is discussed in part B. Next, the effect due to differential mix of

centralized interviewing is examined in part C. Effects due to composite estimation are given in

part D, and seasonal adjustment is discussed in part E. Finally, information on variances for

estimates from 1990-census-based population controls is included in Section II.

I. Effect on laborforce estimates

Included in the table below are some highlights from the questionnaire redesign

and data collection effects found in Polivka (1994). These estimates serve as a basis for

interpreting the effects discussed in this report. It should be noted that

these are 1993 annual average estimates that use 1980-based census population controls

and do not use compositing.

 Table 2. Unemployment Rates

PS CPS PS-CPS

Total 7.26 6.81 0.45*

 Men 7.36 7.08 0.28

 Women 7.14 6.48 0.66*

 16-19 20.61 19.03 1.58*

Adult Men 6.58 6.35 0.23

Adult Women 6.34 5.83 0.51*

*Significant at the 10% Level
10

A. Effect of 1990-based population controls

 In January 1994, the CPS began controlling to the 1990-census-based population

controls adjusted for undercount. To examine the effect of this change, monthly

CPS data for 1993 were weighted using each set of controls--those based on the

1980 census and those based on the 1990 census. Results for the 1993 annual

averages are presented.

The data showing the effect of the switch in population controls on CPS are given

in tables A-1 through A-3. These results show:

• An increase in estimated levels for all major laborforce categories. 

Relatively speaking, the increase was largest for unemployed (over 2

percent) and smallest for not in laborforce (less than .2 percent). The other

categories (employed, CLF, CNP16+) increased from .6 to .9 percent.

(See table A-1.)

• The unemployment rates estimated using 1990-based controls were

greater than the rates using 1980-based controls for most demographic

groups. The overall increase was .1 percentage point. (See table A-2.)

• Using the 1990 controls tends to result in larger laborforce participation

rates. Percentage point increases vary from .04 to 1.01, with an overall

increase of .15 percentage point. These new controls did cause a slight

decrease for white females and teenagers. (See table A-3.) 

• Some comparable 1980-and 1990-based figures for the PS are

given in table A-4. These results are consistent with those given in

table A-1 for the CPS; however, the estimates given above for the

CPS more accurately reflect the effect on CPS estimates and

because of CPS's larger sample size, are considerably more

reliable.

No formal statistical testing was conducted for any of the above comparisons. 

Because the same sample data were used to construct both sets of estimates, the

variances on the differences are believed to be very small. Thus, most of these

differences would likely be significant. 

Additional information on the effect of the switch to 1990-based population

controls is given in the February 1994 Employment and Earnings (Bureau of

Labor Statistics, 1994, Vol. 41, No. 2). The data show that Hispanic estimates

were affected the most by this change.
11

B. Effect of fewer post-stratification controls

As noted above, the PS used fewer post-stratification controls than the CPS. The

PS did not control to State population estimates and used fewer national

race/sex/age ethnicity controls because of the much smaller sample size. 

Concerns over whether this could be contributing to differences attributed to the

redesign, led us to reweight the CPS using the exact same post-stratification

controls used for the PS. Thus, to examine the effect of these differences in

estimation procedures, we compiled three sets of estimates, all using the 1990

census-based controls. Here we compare PS estimates with CPS estimates using

the CPS post-stratification controls and with reweighted CPS (RCPS) estimates

using the PS post-stratification controls. 

Tables B-1 through B-3 contain 1993 annual average estimates of unemployment

rates, employment to population ratios and civilian laborforce participation rates

for each of the three methods. Some highlights:

• The differences in the unemployment rates do not change when CPS is

reweighted with fewer post-stratification controls. All estimated

differences are not significant, even the .10 increase for black men. (See

table B-1.)

• Overall, the reweighting has no significant effect on the employment-topopulation ratios. (See table B-2.)

• For the civilian laborforce, again we get no significant effect. (See table

B-3.)

In conclusion, the difference in number of post-stratification controls does not

have a significant effect on comparisons between the CPS and PS as documented

by Polivka (1994).

Note: Use of 1990-based population controls give different results than those estimated by

Polivka (1994) which used 1980-based population controls. For example, the .45 percentage

point difference in the estimated unemployment rates using the 1980-based population controls

is estimated as .47 when the 1990-based population controls are used. This is because the 1990-

based population controls raise the CPS estimated unemployment rate by .10 percentage point,

while raising the PS estimated unemployment rate by .12 percentage point, as shown in part A

above.
12

C. Effect of differential proportions of centralized interviewing

The estimated redesign effects discussed by Polivka (1994) are partially

attributable to differences in the proportion interviewed from a central location. 

During 1993, approximately 9 percent of the CPS sample was interviewed from a

centralized facility, while 18 percent of the PS sample was interviewed from a

centralized facility. In January 1994, approximately 12.5 percent of the CPS

sample was interviewed from a centralized telephone facility. To obtain a

measure of how this affects January 1994 CPS data, we reweighted the PS to

reflect the proportion of centralized interviewing that was to occur in the January

1994 CPS (12.5 percent). The reweighting of the PS involved adjusting base

weights within test (eligible for centralized interviewing) and control (not

eligible for centralized interviewing) panels, and then performing the usual poststratification. Annual average estimates for 1993 from the reweighted PS were

compared to those from the CPS. The 1990-based population controls were used

for both surveys, resulting in estimated differences between the PS and the CPS

which are not exactly the same as those estimated by Polivka (1994). 

The data showing the estimated effect of different proportions of centralized

interviewing are given in tables C-1, C-2, and C-3. These results show:

• The reweighted PS (RPS) gives an estimated unemployment rate of 7.29

compared to 7.37 in the PS. These unemployment rates were close to

being significant at the 90 percent confidence level. The estimated

increase of .47 percentage point on the unemployment rate is partially due

to differences in the percent of centralized interviews. When the PS is

reweighted to reflect the lower percent of centralized interviewing in

January 1994, we estimate a difference of .39. These estimated

differences between the RPS and the CPS give a more accurate estimate

of the CPS change from December 1993 to January 1994. In general, for

most demographic groups shown, we would expect the effects of the

redesign and collection procedures on the estimated unemployment rate to

be slightly less than previously estimated. (See table C-1.) 

• Tables C-2 and C-3 give the results for employment-to-population ratios

and the civilian laborforce participation rate. No significant differences

between the PS and RPS were found for any of the figures in these tables.

Thus, there is no evidence that the proportion of the sample interviewed

from centralized facilities affects previously estimated redesign effects for

employment and civilian labor force rates.

D. Effect of composite estimator
13

The primary purpose of the composite estimator is to reduce the variance on

estimates of month-to-month change, particularly for employment and civilian

laborforce characteristics. The composite estimator changes the expected value

of an estimate relative to the estimate after post- stratification (uncomposited). 

This is a result of the way the sample rotates; that is, in for 4 months, out for 8

and then in for 4 more months. It has been shown that the expected value of an

estimate depends on the number of times its rotation group has been in the

sample. Furthermore, these differences in expected value, commonly referred to

as rotation group bias but are actually month-in-sample bias, are not necessarily

constant over time. See Bailar (1975). The composite estimator changes the

expected value by differentially weighting the rotation groups. The current

composite estimator was selected based on variance reduction capabilities, its low

bias (relative to the uncomposited estimate), and that it was not sensitive to

changes in rotation group bias. See Kostanich and Bettin (1980).

In January 1994, no compositing is used with the CPS. The compositing will

begin in the early months of 1994 but will take several months before becoming

stable. To estimate the effect of compositing on the unemployment rate, PS and

CPS estimates, using both 1980 and 1990-based population controls, were

composited with the initial composited month being October 1992. The resulting

1993 annual averages are presented in table D-1. Major findings from the 1990

based estimates are:

• The 1993 annual average of composited monthly estimates of the

unemployment rate from the PS is estimated to be .06 percentage point

lower than the comparable uncomposited estimate from the PS. However,

from CPS, we estimate an increase of .02 percentage point from the

composite.

• The difference between PS and CPS diminishes slightly when the

composite is used (.47 to .39 percentage point).

These results may not be indicative of the composite estimator's long term effect.

 As noted above, the expected value of the composite estimator is affected by the

number of times the rotation group has been in the sample. Since the PS had a

short phase-in, the historical month-in-sample pattern is not present in the PS

data. Consequently, it is not surprising that a composite estimator developed for

the CPS month-in-sample bias pattern has a different effect when used with the

PS. In any event, the composite estimate has very little effect on the expected

value of monthly estimates. This was examined extensively under a variety of

bias and change assumptions. See Cantwell and Ernst (1994).

E. Seasonal adjustment procedure
14

A seasonally adjusted national unemployment rate for CPS is produced by

aggregating 12 independently adjusted series. The component series are: 

agricultural employment, nonagricultural employment, and unemployment by

four sex-age groups (men 20 years and over, women 20 years and over, men 16 to

19 years, and women 16 to 19 years). Eight of these series are seasonally

adjusted using multiplicative factors; the other four use additive factors. The four

additive series are nonagricultural men and women of age 16 to 19 years, and

unemployed men and women of age 16 to 19 years. The seasonal adjustment

factors are generated using X-11 ARIMA software and are given in January 1994

issue of Employment and Earnings. Each of these 12 series is separately adjusted

for seasonal variation, and the resulting estimates are then aggregated to derive

seasonally adjusted totals. The seasonally adjusted figure for the laborforce is a

sum of eight seasonally adjusted civilian employment components and four

seasonally adjusted unemployment components. The overall unemployment rate

is derived by dividing the resulting estimate of total unemployment by the

estimate of the laborforce.

As part of our research, we applied the same seasonal methods to both the CPS

and the initial parallel survey estimates for each month of January 1993 to

December 1993 data. Our results indicate that the monthly difference in the

estimates of unemployment rate between the CPS and the initial parallel survey,

after applying the seasonal adjustments was the same as before the seasonal

adjustment. In other words, the seasonal adjustment moved the two series in the

same direction by about the same absolute amount. It will, however, take several

years before the seasonal pattern of the "new" CPS are formed.

II. Variance effects from 1990-based population controls

In general, a standard error of an estimated level increases as the size of the estimate

increases. Because the 1990-based population controls tend to increase the level of

estimates, we expect the switch to the 1990-based population controls in January 1994

will increase the variability of estimates. Here we compare standard errors on estimates

based on 1980 population controls with those based on 1990 population controls. The

1980-based standard errors (SE80) are estimated using current generalized variance

functions that were derived from 1987 CPS replicate variances. The 1990-based standard

errors were estimated directly using replication from 1993 CPS data post-stratified with
15

1990-based population controls. These results are summarized in tables E-1, E-2, and E3. Some highlights are:

 

• For the total estimated unemployment rate, the estimated standard error is 9

percent larger when 1990-census-based population controls are used. See table

E-1. For demographic groups, the relative increase on the estimated standard

error of the unemployment rate varies from 2 to 6 percent. However, the increase

for blacks is 12 percent, whereas the teenager standard error is lower by 7

percent.

• The estimated standard error on the employment-to-population ratio using 1990

controls is 11 percent higher than using 1980 controls. Increases in this standard

error occur for men and women. The standard error for adult men is actually

lower using 1990 controls. (See table E-2.) 

• The estimated standard error on the laborforce participation rate is 13 percent

higher. For all men, the standard error is 13 percent higher and for all women it

is 11 percent higher. For adult men, however, the standard error is 11 percent

lower, while for adult women it is only 3 percent higher. (See table E-3.)
16

Summary

In general, the most important design difference not reflected in the questionnaire and redesign

effects given in Polivka (1994) are those due to the 1990-based population controls. Switching

to the 1990-based controls has the effect of increasing totals, unemployment rates and laborforce

participation rates for most demographic groups. 

The least important design difference is the use of fewer post-stratification controls in PS. All

estimated effects on unemployment rates, employment-to-population ratios and civilian

laborforce rates were not only small but were also found to be nonsignificant.

The differential proportion of centralized interviewing is probably contributing somewhat to the

redesign effects discussed by Polivka (1994). We suspect that the redesign effects for

unemployed are slightly overstated. However, there is no evidence that differential proportions

of centralized interviewing has affected the redesign effects for employment and civilian

laborforce.

The effects from compositing are expected to be anywhere from a decrease of .06 percentage

point to an increase of .02 percentage point for unemployed. It will be awhile before we can

more precisely estimate the effect of compositing.

The effects due to seasonal adjustment are a lot less clear. We would expect these effects to be

small, but, until more data become available, we won't be able to tell.
17

References

Bailar, B. (1975), The Effects of Rotation Group Bias on Estimates from Panel Surveys, 

Journal of the American Statistical Association, 70, 23-30.

Bregger, John E. and Dippo, Cathryn S. (1993), Overhauling the Current Population Survey: 

Why Is It Necessary to Change? The Monthly Labor Review, Bureau of Labor Statistics,

Washington, D.C.

Bureau of Labor Statistics (1994), Employment and Earnings, Vol. 41, No. 1, Washington, D.C.,

U.S. Department of Labor.

Bureau of Labor Statistics (1994), Employment and Earnings, Vol. 41, No. 2, Washington, D.C.,

U.S. Department of Labor.

Bureau of Labor Statistics (1994), The Employment Situation: January 1994, Washington,

 D.C., U.S. Department of Labor. 

Cantwell, Patrick J. and Ernst, Lawrence R. (1994), Short-Term Changes to the CPS

Composite Estimator in January 1994, Proceedings of the Section on Survey Research

Methods, American Statistical Association.

Kostanich, Donna L. and Bettin, Paul J. (1980), Choosing a Composite Estimator for CPS,

International Symposium on Panel Surveys, Washington, D.C.

Kostanich, Donna L. (1994), Mode Effects Analysis - Highlights. Mode Effects Analysis 

CPS Overlap Analysis Team Technical Report 3. Bureau of the Census, Washington,

D.C.

Miller, Stephen M. (1994), What Would the Unemployment Rate Have Been Had the

Redesigned Current Population Survey Been in Place from September 1992 to December 1993?:

 A Measurement Error Analysis. CPS Bridge Team Technical

Report 1. Bureau of Labor Statistics, Washington, D.C.

Polivka, Anne E. (1994), Comparisons of Labor Force Estimates for the Parallel Survey and the

Current CPS. Overlap Analysis Team Technical Report 1. Bureau of Labor Statistics,

Washington, D.C. 

Rothgeb, Jennifer M. (1994), Revision to the CPS Questionnaire Effect on Data Quality, CPS

Overlap Analysis Team Technical Report 2, Bureau of the Census, Washington, D.C.
Shoemaker, Harland H. (1993), Results from the Current Population Survey CATI PhaseIn Project, Proceedings of the Section on Survey Research Methods, American Statistical

Association.
Table A-1

 EFFECT OF 1990-BASED CONTROLS - CPS

Labor Force Characteristics

(CPS, 1993 Annual Averages)

(Totals in thousands)

1990-Based

Estimate

1980-Based

Estimate

Difference

1990 - 1980

Employed 120,323 119,389 934

Unemployed 8,917 8,714 203

Civilian Labor Force 129,240 128,103 1,137

Not in Labor Force 65,565 65,447 118

Civilian Population 16+ 194,804 193,550 1,254

Labor Force Participation Rate 66.34 66.19 0.15

Employment to Population Ratio 61.77 61.68 0.09

Unemployment Rate 6.90 6.80 0.10
Table A-2

EFFECT OF 1990-BASED CONTROLS

Unemployment Rate

(CPS, 1993 Annual Averages)

1990-Based 1980-Based Difference

Estimate Estimate 1990 - 1980

Total 6.90 6.80 0.10

 Men 7.17 7.07 0.10

 Women 6.57 6.48 0.09

White 6.03 5.96 0.07

 Men 6.32 6.23 0.09

 Women 5.69 5.62 0.07

Black 13.04 12.96 0.08

 Men 13.92 13.89 0.03

 Women 12.18 12.05 0.13

16-19 19.06 19.03 0.03

Adult Men 6.42 6.35 0.07

Adult Women 5.90 5.83 0.07
Table A-3

EFFECT OF 1990-BASED CONTROLS

Civilian Labor Force Rate

(CPS, 1993 Annual Averages)

1990-Based 1980-Based Difference

Estimate Estimate 1990 - 1980

Total 66.34 66.19 0.15

 Men 75.47 75.21 0.26

 Women 57.95 57.91 0.04

White 66.80 66.74 0.06

 Men 76.25 76.10 0.15

 Women 57.97 58.03 -0.06

Black 63.20 62.51 0.69

 Men 69.53 68.52 1.01

 Women 58.07 57.56 0.51

16-19 51.60 51.62 -0.02

Adult Men 77.27 76.92 0.35

Adult Women 58.54 58.46 0.08
Table A-4

 EFFECT OF 1990-BASED CONTROLS - PS

Labor Force Characteristics

(PS, 1993 Annual Averages)

(Totals in thousands)

1990-Based

Estimate

1980-Based

Estimate

Difference

1990 - 1980

Employed 120,511 119,606 905

Unemployed 9,592 9,359 233

Civilian Labor Force 130,103 128,965 1,138

Not in Labor Force 64,702 64,585 117

Civilian Population 16+ 194,805 193,549 1,256

Labor Force Participation Rate 66.79 66.63 0.16

Employment to Population Ratio 61.86 61.80 0.06

Unemployment Rate 7.37 7.26 0.11
Table B-1

EFFECT OF FEWER POST-STRATIFICATION CONTROLS

Unemployment Rate

(1990-Based Population Controls, 1993 Annual Averages)

(RCPS is CPS Reweighted with Fewer Controls)

 Differences

PS CPS RCPS PS - CPS PS - RCPS

Total 7.37 6.90 6.89 0.47 0.48

 Men 7.47 7.17 7.16 0.30 0.31

 Women 7.26 6.57 6.56 0.69 0.70

White 6.39 6.04 6.03 0.35 0.36

 Men 6.54 6.32 6.31 0.22 0.23

 Women 6.21 5.69 5.67 0.52 0.54

Black 14.38 13.04 12.98 1.34 1.40

 Men 15.00 13.92 13.82 1.08 1.18

 Women 13.80 12.18 12.16 1.62 1.64

16-19 20.60 19.06 19.08 1.54 1.52

Adult Men 6.66 6.42 6.40 0.24 0.26

Adult Women 6.44 5.90 5.90 0.54 0.55

No significant differences between CPS & RCPS were found.
Table B-2

EFFECT OF FEWER POST-STRATIFICATION CONTROLS

Employment Rate

(1990-Based Population Controls, 1993 Annual Averages)

(RCPS is CPS Reweighted with Fewer Controls)

 Differences

PS CPS RCPS PS - CPS PS - RCPS

Total 61.86 61.77 61.78 0.09 0.08

 Men 69.47 70.05 70.07 -0.58 -0.59

 Women 54.86 54.14 54.16 0.72 0.70

White 63.00 62.77 62.79 0.23 0.21

 Men 70.89 71.43 71.44 -0.54 -0.55

 Women 55.61 54.67 54.69 0.94 0.92

Black 53.91 54.96 54.99 -1.05 -1.08

 Men 58.16 59.85 59.86 -1.69 -1.70

 Women 50.46 51.00 51.03 -0.53 -0.57

16-19 42.84 41.76 41.70 1.08 1.15

Adult Men 71.65 72.32 72.34 -0.66 -0.69

Adult Women 55.75 55.09 55.11 0.66 0.64
Table B-3

EFFECT OF FEWER POST-STRATIFICATION CONTROLS

Civilian Labor Force Rate

(1990-Based Population Controls, 1993 Annual Averages)

(RCPS is CPS Reweighted with Fewer Controls)

 Differences

PS CPS RCPS PS - CPS PS - RCPS

Total 66.79 66.34 66.35 0.45 0.44

 Men 75.07 75.47 75.47 -0.40 -0.40

 Women 59.16 57.95 57.96 1.21 1.20

White 67.30 66.80 66.81 0.50 0.49

 Men 75.86 76.25 76.25 -0.39 -0.39

 Women 59.29 57.97 57.98 1.32 1.31

Black 62.97 63.20 63.19 -0.23 -0.22

 Men 68.43 69.53 69.47 -1.10 -1.04

 Women 58.54 58.07 58.10 0.47 0.44

16-19 53.96 51.60 51.50 2.36 2.47

Adult Men 76.76 77.27 77.29 -0.51 -0.53

Adult Women 59.59 58.54 58.56 1.05 1.03

No significant differences between CPS & RCPS were found.
Table C-1

EFFECT OF DIFFERENTIAL PROPORTIONS OF CENTRALIZED INTERVIEWING

Unemployment Rate

(1990-Based Population Controls, 1993 Annual Averages)

(RPS is PS Reweighted to 1/94 CPS Proportions)

Differences

PS RPS CPS PS - CPS RPS - CPS

Total 7.37 7.29 6.90 0.47 0.39

 Men 7.47 7.42 7.17 0.30 0.25

 Women* 7.26 7.14 6.57 0.69 0.57

White 6.39 6.34 6.04 0.35 0.30

 Men 6.54 6.51 6.32 0.22 0.19

 Women 6.21 6.15 5.69 0.52 0.46

Black 14.38 14.07 13.04 1.34 1.03

 Men 15.00 15.00 13.92 1.08 1.08

 Women* 13.80 13.19 12.18 1.62 1.01

16-19 20.60 20.69 19.06 1.54 1.63

Adult Men 6.66 6.64 6.42 0.24 0.22

Adult Women* 6.44 6.25 5.90 0.54 0.35

 * Differences between PS & RPS significant at the 10 % level.

 
Table C-2

EFFECT OF DIFFERENTIAL PROPORTIONS OF CENTRALIZED INTERVIEWING

Employment Rate

(1990-Based Population Controls, 1993 Annual Averages)

(RPS is PS Reweighted to 1/94 CPS Proportions)

 Differences

PS RPS CPS PS - CPS RPS - CPS

Total 61.86 61.97 61.77 0.09 0.20

 Men 69.47 69.51 70.05 -0.58 -0.54

 Women 54.86 55.02 54.14 0.72 0.88

White 63.00 63.11 62.77 0.23 0.34

 Men 70.89 70.96 71.43 -0.54 -0.47

 Women 55.61 55.76 54.67 0.94 1.09

Black 53.91 53.91 54.96 -1.05 -1.05

 Men 58.16 57.81 59.85 -1.69 -2.04

 Women 50.46 50.75 51.00 -0.54 -0.25

16-19 42.84 42.90 41.76 1.08 1.14

Adult Men 71.65 71.71 72.32 -0.67 -0.61

Adult Women 55.75 55.90 55.09 0.66 0.81

No significant differences between PS & RPS were found.
Table C-3

EFFECT OF DIFFERENTIAL PROPORTIONS OF CENTRALIZED INTERVIEWING

Civilian Labor Force Rate

(1990-Based Population Controls, 1993 Annual Averages)

(RPS is PS Reweighted to 1/94 CPS Proportions)

Differences

PS RPS CPS PS - CPS RPS - CPS

Total 66.79 66.84 66.34 0.45 0.50

 Men 75.07 75.08 75.47 -0.40 -0.39

 Women 59.16 59.25 57.95 1.21 1.30

White 67.30 67.38 66.80 0.50 0.58

 Men 75.86 75.90 76.25 -0.39 -0.35

 Women 59.29 59.41 57.97 1.32 1.44

Black 62.97 62.73 63.20 -0.23 -0.47

 Men 68.43 68.01 69.53 -1.10 -1.52

 Women 58.54 58.46 58.07 0.47 0.39

16-19 53.96 54.09 51.60 2.36 2.49

Adult Men 76.76 76.81 77.27 -0.51 -0.46

Adult Women 59.59 59.63 58.54 1.05 1.09

No significant differences between PS & RPS were found.
Table D-1

EFFECT OF COMPOSITE ESTIMATOR

Unemployment Rate

(1990-Based Population Controls, 1993 Annual Averages)

 Uncomposited Composited

PS CPS PS-CPS PS CPS PS-CPS

Total 7.37 6.90 0.47 7.31 6.92 0.39

 Men 7.47 7.17 0.30 7.42 7.18 0.24

 Women 7.26 6.57 0.69 7.18 6.61 0.57

16-19 20.60 19.13 1.47 20.59 19.07 1.52

Adult Men 6.66 6.42 0.24 6.60 6.44 0.16

Adult Women 6.44 5.90 0.54 6.37 5.94 0.43
Table D-2

EFFECT OF COMPOSITE ESTIMATOR

Unemployment Rate

(1980-Based Population Controls, 1993 Annual Averages)

 Uncomposited Composited

PS CPS PS-CPS PS CPS PS-CPS

Total 7.26 6.80 0.45 7.19 6.82 0.37

 Men 7.36 7.08 0.28 7.31 7.09 0.22

 Women 7.14 6.48 0.66 7.06 6.51 0.55

16-19 20.61 19.10 1.51 20.57 19.03 1.54

Adult Men 6.58 6.35 0.23 6.52 6.37 0.15

Adult Women 6.34 5.83 0.51 6.27 5.87 0.40
Table E-1

EFFECT OF 1990-BASED CONTROLS ON STANDARD ERRORS

Unemployment Rate

(CPS, 1993 Annual Averages)

 1990-Based 1980-Based Ratio of SEs

Estimate SE Estimate SE 1990 to 1980

Total 6.90 0.12 6.80 0.11 1.09

 Men 7.17 0.16 7.07 0.16 1.01

 Women 6.57 0.17 6.48 0.16 1.03

White 6.03 0.12 5.96 0.11 1.06

 Men 6.32 0.16 6.23 0.16 1.02

 Women 5.69 0.16 5.62 0.17 0.99

Black 13.04 0.50 12.96 0.45 1.12

 Men 13.92 0.71 13.89 0.69 1.03

 Women 12.18 0.64 12.05 0.63 1.02

16-19 19.06 0.74 19.03 0.79 0.93

Adult Men 6.42 0.15 6.35 0.15 1.02

Adult Women 5.90 0.16 5.83 0.16 1.01
Table E-2

EFFECT OF 1990-BASED CONTROLS ON STANDARD ERRORS

Employment Rate

(CPS, 1993 Annual Averages)

 1990-Based 1980-Based Ratio of SEs

Estimate SE Estimate SE 1990 to 1980

Total 61.77 0.16 61.68 0.14 1.11

 Men 70.05 0.19 69.88 0.18 1.07

 Women 54.14 0.21 54.16 0.19 1.09

White 62.77 0.16 62.77 0.16 1.00

 Men 71.43 0.20 71.36 0.21 0.98

 Women 54.67 0.22 54.76 0.22 1.01

Black 54.96 0.55 54.40 0.55 1.00

 Men 59.85 0.72 59.00 0.70 1.04

 Women 51.00 0.69 50.62 0.69 1.00

16-19 41.76 0.61 41.80 0.62 0.98

Adult Men 72.32 0.19 72.04 0.21 0.93

Adult Women 55.09 0.22 55.06 0.21 1.03
Table E-3

EFFECT OF 1990-BASED CONTROLS ON STANDARD ERRORS

Civilian Labor Force Rate

(CPS, 1993 Annual Averages)

 1990-Based 1980-Based Ratio of SEs

Estimate SE Estimate SE 1990 to 1980

Total 66.34 0.15 66.19 0.13 1.13

 Men 75.47 0.17 75.21 0.15 1.13

 Women 57.95 0.21 57.91 0.19 1.11

White 66.80 0.15 66.74 0.15 0.99

 Men 76.25 0.18 76.10 0.19 0.95

 Women 57.97 0.22 58.03 0.21 1.03

Black 63.20 0.52 62.51 0.54 0.97

 Men 69.53 0.66 68.52 0.62 1.06

 Women 58.07 0.66 57.56 0.69 0.96

16-19 51.60 0.64 51.62 0.63 1.02

Adult Men 77.27 0.17 76.92 0.19 0.89

Adult Women 58.54 0.21 58.46 0.21 1.03