Household Economic Studies

U.S. Department of Commerce

Economics and Statistics Administration U U.S. CENSUS BUREAU

S C E N S U S B U R E A U

Helping You Make Informed Decisions

Dynamics of Economic Well-Being: 

Poverty, 2004–2006

INTRODUCTION 

This report presents data on poverty 

based on information collected in the 

Survey of Income and Program Participation (SIPP). The report describes patterns 

of poverty using measures with different 

time horizons and provides a dynamic 

view of the duration of poverty spells and 

the frequency of transitions into and out 

of poverty. It further examines how 

poverty dynamics vary across demographic groups. The report focuses on 

data collected in the first 36 months of 

the 2004 Panel of the SIPP (covering 

January 2004 to December 2006), and 

where appropriate, makes comparisons to 

data collected for January 2001 to 

December 2003 in the 2001 SIPP Panel.1

The SIPP and other longitudinal surveys 

allow policy makers, academic researchers, and the general public to paint a more 

detailed portrait of poverty than the one 

provided by the official annual poverty 

estimate. The official annual poverty rate, 

based on the Current Population Survey 

Annual Social and Economic Supplement 

(CPS ASEC), captures a snapshot of wellbeing at a single time period. 

1 The 2004 Panel of the SIPP consisted of 48 

interview months (in 12 waves) and was collected 

from February 2004 to January 2008. The data in this 

report include 36 months from the first 10 waves of 

the 2004 Panel collected from February 2004 to May 

2007. These data are compared to 36 months of data 

from the 2001 Panel collected from February 2001 

to January 2004 in 9 waves. The first 10 waves of 

the 2004 Panel, reference months January 2004 to 

December 2006, were used instead of January 2005 to 

December 2007 to include as much information prior 

to a 53 percent sample cut in the ninth wave. Tables 

A-17 and A-18 show selected 3-year estimates (2004 

to 2006) and 4-year estimates (2004 to 2007). 

Once a year, the CPS ASEC measures the 

percentage of people whose annual family 

money income falls below their official 

poverty threshold but does not address 

how poverty varies across shorter or 

longer time periods or how an individual’s 

poverty status changes over time. Compared with the official annual poverty 

rate, longitudinal research finds poverty 

rates vary by the time period examined—

a small fraction of people are in poverty 

for more than 1 year while a larger percentage of people experience poverty for 

shorter time periods.2

The SIPP interviews a representative 

sample of U.S. households every 

4 months. The population represented 

(the population universe) is the civilian 

noninstitutionalized population of the 

United States. Core content of the SIPP 

identifies the demographic characteristics, 

2 Examples of previous longitudinal studies on 

poverty include: Stephanie R. Cellini, Signe-Mary 

McKernan, and Caroline Ratcliffe, “The Dynamics of 

Poverty in the United States: A Review of Data,

Methods, and Findings,” Journal of Policy Analysis

and Management 27 (2008), pp. 577–605. John 

Iceland, “Dynamics of Economic Well-being: Poverty 

1996–1999,” Current Population Reports, Series P70-

91, U.S. Census Bureau, Washington, DC, 2003.

Mary Naifeh, “Dynamics of Economic Well-Being,

Poverty, 1993–94: Trap Door? Revolving Door? Or 

Both?,” Current Population Reports, Series P70-63,

U.S. Census Bureau, Washington, DC, 1998. SigneMary McKernan and Caroline Ratcliffe, “Transition 

Events in the Dynamics of Poverty, Urban Institute 

Research Report,” 2002, <http://www.urban.org/url

.cfm?ID=410575>. Mary Jo Bane and David Ellwood, 

“Slipping Into and Out of Poverty: The Dynamics of 

Spells,” Journal of Human Resources 21 (1986), pp. 

1–23. Ann Huff Stevens, “The Dynamics of Poverty 

Spells: Updating Bane and Ellwood,” AEA Papers and 

Proceedings 84 (1994), pp. 34–37. Ann Huff Stevens, 

“Climbing Out of Poverty, Falling Back In: Measuring 

the Persistence of Poverty Over Multiple Spells,”

Journal of Human Resources 34 (1999), pp. 557–588.

Issued March 2011

P70-123

By

Robin J. Anderson

Current

Population

Reports
2 U.S. Census Bureau

labor force participation, government program participation, and 

various income sources for members of sampled households. 

Poverty statistics presented in this 

report adhere to the standards 

specified by Office of Management 

and Budget’s Statistical Policy Directive 14. The U.S. Census Bureau 

uses a set of money income thresholds that vary by family size and 

composition to determine who is in 

poverty. If a family’s total income 

is less than that family’s threshold, 

then that family and every individual in it are considered to be in 

poverty. The poverty thresholds do 

not vary geographically. They are 

updated to allow for changes in the 

cost of living using the Consumer 

Price Index (CPI-U).

Since SIPP respondents are interviewed throughout the year and 

asked about their income for the 

previous 4 months individually, 

each month’s income is compared 

to the appropriate monthly poverty 

threshold. Monthly thresholds are 

calculated by multiplying the baseyear annual poverty thresholds by 

an inflation factor relevant to the reference month and then dividing the 

calculated annual threshold by 12. 

This report discusses poverty rate 

estimates for different time periods, measures the length of time 

people remain poor, and follows 

the movement of people into and 

out of poverty. The poverty measures discussed include monthly, 

episodic, annual, and chronic poverty rates. To capture changes in 

poverty status over time, the report 

examines poverty entry rates, poverty exit rates, and the duration of 

poverty spells. See the text box for 

a more detailed description of each 

measure used in this report.

HIGHLIGHTS 

•	 In the 36 month period from

January 2004 to December 2006, 

28.9 percent of the U.S. population were in poverty for at least

2 months while 2.8 percent were 

in poverty for the entire period.3

3 The estimates in this report (which may 

be shown in text, figures, and tables) are 

based on responses from a sample of the 

population and may differ from the actual 

values because of sampling variability or other 

factors. As a result, apparent differences 

between the estimates for 2 or more groups 

may not be statistically significant. All comparative statements have undergone statistical 

testing and are significant at the 90 percent 

confidence level unless otherwise noted.

• Among the people in poverty in

January and February 2004, 23.1 

percent remained in poverty 

throughout the next 34 months. 

• Of the people in poverty in 2004,

11.7 million (41.6 percent) were 

not in poverty in 2006 but more 

than half of those who exited 

poverty continued to have 

income less than 150 percent of 

their poverty threshold. 

• By 2006, 4.2 percent of people

who were not in poverty in 2004 

had entered poverty. 

Monthly Poverty Rate

Percent in poverty in a given month 

using monthly income and a monthly 

threshold. 

Episodic Poverty Rate Percent in poverty for 2 or more 

consecutive months.

Chronic Poverty Rate

Percent in poverty every month of 

the panel used, from January 2004 to 

December 2006 or from January 2001 

to December 2003.

Annual Poverty Rate

Percent in poverty in a calendar year. 

Each individual’s annual poverty status 

is calculated by comparing the sum 

of monthly family income over the 

year to the sum of monthly poverty 

thresholds for the year.*

Length of Poverty Spell

Number of months in poverty. The 

minimum spell length is 2 months 

and spells are separated by 2 or 

more months of not being in poverty. 

Individuals can have more than 1 spell. 

Spells underway in the first interview 

month of the panel are excluded.

Poverty Entry

Based on the annual poverty measures, 

people who were not in poverty in the 

first year of the panel but in poverty in 

a subsequent year. 

Poverty Exit

Based on the annual poverty measure, 

people who were in poverty in the first 

year of the panel but not in poverty in 

a subsequent year.

Poverty Measures Used in This Report

* The annual poverty rate estimates in the SIPP differ from official poverty estimates based on the CPS ASEC. In the CPS ASEC, poverty status is based on responses 

to income questions referring to the previous calendar year and poverty thresholds

are based on family composition in the interview month (February, March, or April). 

The SIPP family composition may vary during the reference period. 
U.S. Census Bureau 3

• For those in poverty for 2 or

more consecutive months

from 2004 to 2006, the median 

length of a poverty spell was

4.5 months. Almost half

of all spells (47.7 percent)

ended within 4 months while

12.4 percent of spells lasted 

more than 24 months. 

• Non-Hispanic Whites had a lower

episodic poverty rate (22.6 

percent) and a shorter median 

poverty spell length (4.0 months) 

than Hispanics and Blacks.4

Blacks had a higher chronic 

poverty rate (8.4 percent) than 

Hispanics (4.5 percent) and nonHispanic Whites (1.4 percent).5 

• Children under 18 years

had a higher episodic poverty 

rate (36.4 percent) and a

higher chronic poverty rate

(4.8 percent) than adults.

The median length of a poverty 

spell for children under 18 years 

(5.2 months) was longer than

the median length of a poverty 

spell for adults 18 to 64 years 

(4.2 months) but shorter than 

the median spell length of adults 

65 years and over (6.7 months).

• People in female-householder

families had a higher episodic 

poverty rate (51.8 percent), 

higher chronic poverty rate

4 Federal surveys, including the SIPP 

2004 Panel, give respondents the option of 

reporting more than one race. These data 

can be shown in two ways: (1) as mutually 

exclusive from other race groups, which may 

be denoted by “alone” or (2) not mutually 

exclusive with other race groups, denoted 

by “alone or in combination with other race 

groups.” The figures, tables, and text in this 

report show race using the first method. The 

SIPP 2001 Panel did not allow respondents 

to report more than one race. Additionally, 

because Hispanics may be any race, data 

in this report for Hispanics overlap data for 

racial groups. Data users should exercise caution when interpreting aggregate results for 

these groups because they consist of many 

distinct subgroups that differ in socioeconomic characteristics, culture, and recency of 

immigration. 5 Black and Hispanic episodic poverty rates 

and median spell lengths were not statistically different.

0 10 20 30 40

Chronic

(In poverty 36 months)

Annual

(In poverty for a calendar year)

Episodic

(In poverty 2 or more months)

Figure 1a.

Selected Poverty Rates: 2001–2003

Note: Panel (2001 to 2003) and yearly estimates contain different samples. Calendar year 

estimates include people in the sample for 12 months whereas panel estimates include 

people in the sample for 36 months. The total number of respondents in each sample are 

as follows: 47,246 in the 3-year panel; 61,527 in 2001; 57,203 in 2002; and 57,903 in 2003.

Source: U.S. Census Bureau, Survey of Income and Program Participation, 2001 Panel. 

For information on confidentiality protection and sampling and nonsampling error,

see <http://www.census.gov/sipp/source.html>.

Percent

2001

2002

2003

2001–2003

Figure 1b.

Selected Poverty Rates: 2004–2006

Note: Panel (2004 to 2006) and yearly estimates contain different samples. Calendar year 

estimates include people in the sample for 12 months whereas panel estimates include 

people in the sample for 36 months. The total number of respondents in each sample are 

as follows: 27,840 in the 3-year panel; 86,128 in 2004; 76,953 in 2005; and 34,372 in 2006. 

In wave 9 of the SIPP 2004 Panel there was a 53 percent sample reduction.

Source: U.S. Census Bureau, Survey of Income and Program Participation, 2004 Panel. 

For information on confidentiality protection and sampling and nonsampling error,

see <http://www.census.gov/sipp/source.html>.

Percent

2004

2005

2006

2004–2006

0 10 20 30 40

Chronic

(In poverty 36 months)

Annual

(In poverty for a calendar year)

Episodic

(In poverty 2 or more months)
4 U.S. Census Bureau

(9.7 percent), and longer median 

poverty spell (6.4 months) 

than people in married-couple 

families.6

• The percentage of people in

poverty for 2 or more months 

declined from 32.3 percent in 

the 2001 Panel to 28.9 percent 

in the first 36 months of the 

2004 Panel.

• The percentage of people in poverty in all 36 months increased 

from 2.4 percent in the 2001 

Panel to 2.8 percent in the first

3 years of the 2004 Panel. 

RESULTS 

Poverty Rate Comparisons: 

2001–2003 vs. 2004–2006 

Figures 1a and 1b show episodic 

poverty rates, annual poverty rates 

and chronic poverty rates from 

the 2001 and 2004 Panels. Annual 

poverty rates for the 3 years of the 

6 Female householders refer to female 

householders, no husband present; male 

householders refer to male householders, 

no wife present.

2001 Panel (2001, 2002, and 2003) 

were not statistically different from 

each other. The 2004 annual poverty rate (10.6 percent) was not

significantly different from the 

2005 and 2006 rates but the 

decrease in the annual poverty 

rate between 2005 (10.9 percent) 

and 2006 (10.4 percent) was 

significant. 

From January 2004 to December 

2006, the percentage of people 

experiencing a poverty spell

(e.g., poor for at least 2 months) 

was 28.9 percent, down from 32.3 

percent during the 36 months of 

the 2001 Panel.

The percentage of people in

poverty for all 36 months of the 

panel increased from 2.4 percent 

in the 2001 Panel to 2.8 percent in 

the 2004 Panel. 

Monthly Poverty Rates

Figure 2 summarizes monthly and 

annual poverty rates for the 2004 

Panel and shows that monthly 

poverty rates exceeded the annual 

poverty rates. For example, the 

May 2004 monthly poverty rate 

(13.5 percent) exceeded the 2004 

annual poverty rate (10.6 percent). Monthly poverty rates, like 

episodic poverty rates, are higher 

than annual poverty rates because 

people are more likely to experience short-term income shortfalls 

than longer-term deficits. A family could be in poverty for a few 

months (based on monthly poverty 

thresholds and monthly family 

income) but have an annual income 

higher than their corresponding 

annual poverty threshold. 

Poverty Entries and Exits

Table 1 summarizes the poverty 

entries and exits from 2004 to 

2005 and from 2004 to 2006. 

Between 2004 and 2005, the number of people who exited poverty 

(8.8 million people) was not statistically different from the number 

of people who entered poverty. 

From 2004 to 2006, 11.7 million 

people exited poverty while 10.1 

million people entered poverty.7

Of people in poverty in 2004, 31.4 

percent were not poor in 2005 and 

41.6 percent were not poor in 2006 

(Table A-14). Of people not poor 

in 2004, 3.5 percent were poor in 

2005 and 4.2 percent were poor in 

2006 (Table A-12).8

7 Exits from poverty from 2001 to 2002 

(9.1 million) and from 2001 to 2003 (11.3 

million) were not significantly different from 

exits from poverty occurring between 2004 

and 2005 (8.8 million) and 2004 and 2006 

(11.7 million), respectively. Entries into 

poverty from 2001 to 2002 (7.5 million) were 

lower than entries between 2004 and 2005 

(8.4 million), whereas entries into poverty 

from 2001 to 2003 (10.4 million) were not 

statistically different from entries from 2004 

to 2006 (10.1 million). The 2001 Panel poverty exits are from Table A-13 and 2001 Panel 

entries are from Table A-11. 8 Entry rates use the people not in poverty 

in 2004 as the base (243 million people) and 

exit rates use people in poverty in 2004 as 

the base (28.1 million people). Even if the 

number of people who entered poverty was 

the same as the number of people who exited 

poverty, entry rates would be smaller than 

exit rates because the base, or the denominator, for poverty entry rates was much larger 

than the base for exit rates.

0

5

10

15

20

Jan-04 Jul-04 Jan-05 Jul-05 Jan-06 Jul-06 Dec-06

Figure 2.

Monthly and Annual Poverty Rates: 2004-2006

Note: Monthly and yearly estimates contain different samples. Monthly estimates include

only respondents in the sample for one month whereas calendar year estimates include

people in the sample for 12 months. 

Source: U.S. Census Bureau, Survey of Income and Program Participation, 2004 Panel. 

For information on confidentiality protection and sampling and nonsampling error,

see <http://www.census.gov/sipp/source.html>.

Percent

Jan 04

14.9 May 04

13.5

Dec 06

13.7

10.9 10.6 10.4

Monthly poverty rate

Annual poverty rate
U.S. Census Bureau 5

While these data show considerable movement into and out of 

poverty, some individuals moving 

out of poverty continued to have 

family income near poverty. Of the 

11.7 million people who exited 

poverty between 2004 and 2006, 

over half (6.3 million) had income 

below 150 percent of their poverty 

threshold. In addition to the 10.1 

million people who entered poverty 

between 2004 and 2006, another 

8.6 million people had income 

decline from above 150 percent of 

their poverty threshold in 2004 to a 

level between 100 and 150 percent of their poverty threshold in 

2006. (Tables A-15 and A-16 show 

the income to poverty ratio for 

2004 compared to 2005 and 2006, 

respectively.)

Poverty Entries

Non-Hispanic Whites had a lower 

poverty entry rate (2.9 percent) 

than Blacks and Hispanics. Children 

had a higher poverty entry rate 

(5.6 percent) than adults. People in 

female-householder families also 

had a higher poverty entry rate 

(7.6 percent) than those in marriedcouple families (3.2 percent).9

9 The poverty entry rate for Blacks (7.8 

percent) was not statistically different from 

the poverty entry rate for Hispanics. The 

poverty entry for people in male-householder 

families (6.1 percent) was also not statistically different from the poverty entry rate of 

unrelated individuals or of people in femalehouseholder families. 

0 2 4 6 8 10

Unrelated individuals

Male-householder families

Female-householder families

Married-couple families

65 years and over

18 to 64 years

Under 18 years

Non-Hispanic

Hispanic

Black alone

White alone, non-Hispanic

White alone

All people

Figure 3.

Poverty Entry Rates: People Not in Poverty in 2004 

but in Poverty in 2006 by Selected Characteristics

Note: Federal surveys, including the SIPP 2004 Panel, give respondents the option of 

reporting more than one race. These data can be shown in two ways (1) as mutually 

exclusive from other race groups, which may be denoted by "alone" or (2) not mutually 

exclusive with other race groups, denoted by "alone or in combination with other race

groups." This figure shows race using the first method. Because Hispanics may be of any

race, data for Hispanics are not mutually exclusive with race. Female householders have

no husband present and male householders have no wife present. 

Source: U.S. Census Bureau, Survey of Income and Program Participation, 2004 Panel.

For information on confidentiality protection and sampling and nonsampling error,

see <http://www.census.gov/sipp/source.html>.

Percent

4.2

3.6

2.3

7.8

8.3

3.6

5.6

3.8

2.9

3.2

7.6

6.1

5.6

Table 1.

Poverty Entries and Exits: 2004–2006 

(Numbers in thousands)

2004

Total

2005 2006

In poverty Not in poverty In poverty Not in poverty

Number

90 percent

C.I. 1 (+/-) Number

90 percent

C.I. 1 (+/-) Number

90 percent

C.I. 1 (+/-) Number

90 percent

C.I. 1 (+/-)

In poverty. . . . . . . . . . . 28,068 19,268 786 8,798 544 16,403 730 11,665 622

Not in poverty. . . . . . . 242,847 8,416 532 234,430 569 10,095 581 232,751 614

1

 A 90 percent confidence interval (C.I.) is a measure of an estimate’s variability. The larger the confidence interval in relation to the size of the estimate,

the less reliable the estimate. 

Source: U.S. Census Bureau, Survey of Income and Program Participation, 2004 Panel. For information on confidentiality protection and sampling and

nonsampling error, see <http://www.census.gov/sipp/source.html>.

Poverty entries Poverty exits
6 U.S. Census Bureau

The 2004 to 2006 poverty entry 

rate was lower than the entry rate 

from 2001 to 2003 for people in 

female-householder families (9.0 to 

7.6 percent) and for non-Hispanic 

Whites (3.3 to 2.9 percent).10 The 

2004 Panel poverty entry rates for 

other demographic groups were 

not statistically different from their 

respective 2001 Panel entry rates. 

10 Cross-panel comparisons in poverty 

measures of people 65 and over should be 

done with caution due to changes in collection and processing of social security income. 

A note at the end of this report discusses the 

changes in poverty measures for adults 65 

and over between the 2001 and 2004 Panels.

(Table A-11 shows 2001 entries and 

Table A-12 shows 2004 entries.)

Poverty Exits

Consistent with their lower entry 

rate, non-Hispanic Whites had 

a higher poverty exit rate (49.6 

percent) than Blacks and Hispanics from 2004 to 2006. Blacks had 

a lower poverty exit rate (29.5 

percent) than Hispanics (42.1 

percent). Children had a poverty 

exit rate (37.6 percent) lower than 

18- to 64-year-old adults (45.8 

percent) but not statistically different from adults age 65 and over 

(32.2 percent). People in femalehouseholder families (33.0 percent) 

had a lower exit rate than people 

in married-couple families (50.3 

percent).11

The poverty exit rate increased for 

unrelated individuals from 36.1 

percent in the 2001 Panel to 41.8 

percent in the 2004 Panel. Exit 

rates did not significantly change 

for any other group. (Table A-13 

shows 2001 rates and Table A-14 

shows 2004 rates.)

Between 2004 and 2006, for the 

total population, 1.6 million more 

people exited poverty than the 

number of people who entered 

poverty but poverty exits did not 

exceed poverty entries for all 

demographic groups. Approximately 900,000 more people in 

married-couple families entered 

poverty (5.4 million) than exited 

poverty (4.5 million). Among the 

other demographic groups, the 

number of people who exited poverty exceeded or was not significantly different from the number of 

people who entered poverty from 

2004 to 2006. (Estimates of the 

number of people entering poverty 

are in Table A-12 while estimates 

of the number exiting poverty are 

in Table A-14.) 

Episodic Poverty Rates

From 2004 to 2006, non-Hispanic 

Whites had a lower episodic

poverty rate (22.6 percent) than

Blacks (45.5 percent) and Hispanics 

(45.8 percent). Black and Hispanic 

episodic poverty rates were not 

statistically different from each 

other. 

The episodic poverty rate for

children under 18 years (36.4 percent) was higher than the episodic 

poverty rates for adults. Adults

11 The exit rate for people in marriedcouple families (50.3 percent) was not statistically different from the exit rate for people 

in male-householder families (50.8 percent).

Unrelated individuals

Male-householder families

Female-householder families

Married-couple families

65 years and over

18 to 64 Years

Under 18 years

Not Hispanic

Hispanic

Black alone

White alone, not Hispanic

White alone

All people

Figure 4.

Poverty Exit Rates: People in Poverty in 2004 but 

Not in Poverty in 2006 by Selected Characteristics

Note: Federal surveys, including the SIPP 2004 Panel, give respondents the option of 

reporting more than one race. These data can be shown in two ways (1) as mutually 

exclusive from other race groups, which may be denoted by "alone" or (2) not mutually 

exclusive with other race groups, denoted by "alone or in combination with other race 

groups." This figure shows race using the first method. Because Hispanics may be of any 

race, data for Hispanics are not mutually exclusive with race. Female householders have 

no husband present and male householders have no wife present. 

Source: U.S. Census Bureau, Survey of Income and Program Participation, 2004 Panel.

For information on confidentiality protection and sampling and nonsampling error,

see <http://www.census.gov/sipp/source.html>.

Percent

0 10 20 30 40 50 60

Unrelated individuals

Male-householder families

Female-householder families

Married-couple families

65 years and over

18 to 64 years

Under 18 years

Non-Hispanic

Hispanic

Black alone

White alone, non-Hispanic

White alone

All people
U.S. Census Bureau 7

65 years and over had a lower 

episodic poverty rate (18.1 percent) 

than adults aged 18 to 64

(27.7 percent). 

The episodic poverty rate for 

people in female-householder 

families (51.8 percent) exceeded 

the episodic poverty rates for 

people in other types of families. 

People in married-couple families 

had the lowest episodic poverty 

rate (20.9 percent). The episodic poverty rate for unrelated 

individuals (39.4 percent) was 

not statistically different from the 

episodic poverty rate for people in 

male-householder families 

(37.3 percent). 

Most of the demographic groups 

examined had a lower episodic 

poverty rate in the 2004 Panel than 

in the 2001 Panel. 12

12 The episodic poverty rate for people in 

male-householder families in the 2001 Panel 

was not statistically different from the rate 

in the 2004 Panel. The 2001 Panel episodic 

poverty rates can be found in Table A-1.

Chronic Poverty Rates 

As was the case with episodic 

poverty rates, children had a higher 

chronic poverty rate (4.8 percent) 

than adults and the chronic poverty 

rate for non-Hispanic Whites (1.4 

percent) was lower than the chronic 

poverty rates for Hispanics and 

Blacks. On the other hand, unlike 

the patterns found in episodic poverty rates, the chronic poverty rate 

for adults 18 to 64 (1.9 percent) 

was lower than the rate for adults 

65 years and over (3.0 percent) and 

Blacks had a higher chronic poverty 

rate (8.4 percent) than Hispanics 

(4.5 percent).

By family type, chronic poverty 

rates exhibited a pattern similar 

to the pattern for episodic poverty 

rates. The chronic poverty rate 

for people in female-householder 

families (9.7 percent) was higher 

than the chronic poverty rates for 

people in other types of families. 

People in married-couple families 

had the lowest chronic poverty rate 

(0.7 percent). 

In contrast to the general pattern 

of declining episodic poverty rates 

from the 2001 Panel to the 2004 

Panel, chronic poverty rates for 

some groups increased. (Estimates 

from the 2001 Panel can be found 

in Table A-3.) The chronic poverty 

rate for Blacks increased from 6.6 

percent to 8.4 percent; the chronic 

poverty rate for children increased 

from 3.2 percent to 4.8 percent; 

the chronic poverty rate for people 

in female-householder families 

increased from 6.8 percent to 9.7 

percent; and the chronic poverty 

rate for people in male-householder 

families increased from 1.1 percent 

to 2.6 percent. Chronic poverty 

rates for Hispanics, non-Hispanic

Whites, adults 18 to 64, and people 

Unrelated 

Male-househo

Female-househo

Married-co

65 ye

18 

Un

White alone, 

Figure 5.

Episodic Poverty (People in Poverty for 2 or More 

Months) by Selected Characteristics: 2004–2006

Note: Federal surveys, including the SIPP 2004 Panel, give respondents the option of 

reporting more than one race. These data can be shown in two ways (1) as mutually 

exclusive from other race groups, which may be denoted by "alone" or (2) not mutually 

exclusive with other race groups, denoted by "alone or in combination with other race 

groups." This figure shows race using the first method. Because Hispanics may be of any 

race, data for Hispanics are not mutually exclusive with race. Female householders have 

no husband present and male householders have no wife present. 

Source: U.S. Census Bureau, Survey of Income and Program Participation, 2004 Panel.

For information on confidentiality protection and sampling and nonsampling error,

see <http://www.census.gov/sipp/source.html>.

Percent

0 10 20 30 40 50 60

Unrelated individuals

Male-householder families

Female-householder families

Married-couple families

65 years and over

18 to 64 years

Under 18 years

Non-Hispanic

Hispanic

Black alone

White alone, non-Hispanic

White alone

All people
8 U.S. Census Bureau

in married-couple families did not 

change significantly.13

The Distribution of People

by Poverty Status

Figure 7 compares the population experiencing either chronic 

13 From 2001 to 2003, the chronic poverty 

rate was 1.3 percent for White non-Hispanics, 

3.8 percent for Hispanics, 1.8 percent for 

adults 18 to 64 years old, and 0.6 percent 

for people in married-couple families (Table 

A-3). The chronic poverty rate for unrelated 

individuals declined from 6.2 percent to 5.2 

percent from the 2001 to 2004 Panel (Tables 

A-3 and A-4). Cross-panel comparisons in the 

poverty rates of people aged 65 and over 

should be done with caution due to changes 

in collection and processing of social security 

income data. A note at the end of this report 

discusses the changes in poverty measures 

for adults 65 years and over between the 

2001 and 2004 Panels. 

or episodic poverty to the total 

population.14 While children made 

up about 26 percent of the total 

population, they represented 

approximately 33 percent of those 

who were poor at least 2 months 

and about 45 percent of those who 

were poor for the entire 36 months. 

Similarly, Blacks were 12.5 percent 

of the entire population, 19.6 percent of the population with at least 

1 poverty spell, and 37.6 percent 

of the chronically poor. People 

in female-householder families 

were 14.4 percent of the population, 25.8 percent of those with a 

14 The population excluded people not in 

the poverty universe. Calculations derived 

from estimates in Tables A-2 and A-4.

poverty spell, and almost

50 percent of the chronically poor. 

On the other hand, the percentage 

of the chronically poor population 

that was 65 years and over (11.8 

percent) was not statistically different than the percentage of the 

total population that was 65 years 

and over. People in married-couple 

families made up 65.9 percent of 

the total population but 47.7 percent of the population with at least 

1 poverty spell, and 17.0 percent of 

the chronically poor. 

Between the 2001 Panel and the 

2004 Panel, the percentage of the 

chronically poor who were children 

increased from 35.6 percent to 

44.9 percent.15 On the other hand, 

the percentage of the chronically 

poor who were adults 65 years and 

over fell from 17.7 percent to 11.8 

percent.16

The Risk of Chronic Poverty

Figure 8 presents the people who 

were in poverty all 36 months 

from 2004 to 2006 as a proportion 

of people who were in poverty in 

January and February 2004. About 

23 percent of the people in poverty 

for the first 2 months of the 2004 

Panel were in poverty for the entire 

3-year period. 

Blacks in poverty for the first

2 months of the 2004 Panel were 

more likely to be poor all 36 

months than non-Hispanic Whites 

and Hispanics. The percentage of 

15 The percent of the episodically poor 

population who were children in the 2004 

Panel (32.8 percent) was not statistically

different from the 2001 Panel (33.2 percent). 

The 2001 Panel calculations are derived from 

estimates in Tables A-1 and A-3. 16 The decline in the proportion of the 

chronically poor population 65 years and 

over (and increase in the proportion that 

were children) may be partially attributed to 

changes in the SIPP instrument. Cross-panel 

comparisons in the poverty rates of people 

65 and over should be done with caution due 

to changes in collection and processing of 

social security income data. A note at the end 

of this report discusses the changes in poverty measures for adults 65 years and over 

between the 2001 and 2004 Panels. 

Figure 6.

Chronic Poverty (People in Poverty All 36 Months) 

by Selected Characteristics: 2004–2006

Note: Federal surveys, including the SIPP 2004 Panel, give respondents the option of 

reporting more than one race. These data can be shown in two ways (1) as mutually 

exclusive from other race groups, which may be denoted by "alone" or (2) not mutually 

exclusive with other race groups, denoted by "alone or in combination with other race 

groups." This figure shows race using the first method. Because Hispanics may be of any 

race, data for Hispanics are not mutually exclusive with race. Female householders have 

no husband present and male householders have no wife present. 

Source: U.S. Census Bureau, Survey of Income and Program Participation, 2004 Panel. 

For information on confidentiality protection and sampling and nonsampling error,

see <http://www.census.gov/sipp/source.html>.

Percent

7

0 2 4 6 8 10

Unrelated individuals

Male-householder families

Female-householder families

Married-couple families

65 years and over

18 to 64 years

Under 18 years

Non-Hispanic

Hispanic

Black alone

White alone, non-Hispanic

White alone

All people
U.S. Census Bureau 9

Figure 7.

Distribution of People by Poverty Status, and Selected Characteristics: 2004–2006

Note: The poverty universe excludes unrelated children under 15 years old. Federal surveys, including the SIPP 2004 Panel, give respondents 

the option of reporting more than one race. These data can be shown in two ways (1) as mutually exclusive from other race groups, which 

may be denoted by "alone" or (2) not mutually exclusive with other race groups, denoted by "alone or in combination with other race groups." 

This figure shows race using the first method. Because Hispanics may be of any race, data for Hispanics are not mutually exclusive with race. 

Female householders have no husband present and male householders have no wife present. 

Source: U.S. Census Bureau, Survey of Income and Program Participation, 2004 Panel. For information on confidentiality protection and sampling 

and nonsampling error, see <http://www.census.gov/sipp/source.html>.

(Percent)

26.1 63.0

32.8

44.9

11.0

60.4 6.9

43.3 11.8

Under 18 years 18 to 64 years 65 years and over

Panel A

Age

Population

(270.9 million)

Episodically poor

(78.3 million)

Chronically poor

(7.6 million)

80.7 12.5

72.5

54.5

6.8

19.6 7.8

37.6 7.9

White alone Black alone Other race groups

Panel B

Race

15.6 14.4 4.1

21.2

29.2

65.9

5.3

3.8

25.8 47.7

49.9 17.0

Unrelated 

individuals

Female-householder

families

Male-householder

families

Married-couple families

Panel C

Family Type

Population

Episodically poor

Chronically poor

Population

Episodically poor

Chronically poor
10 U.S. Census Bureau

Hispanics in poverty in January 

and February 2004 who remained 

in poverty throughout the entire 

3-year period was not statistically 

different from the same estimate 

for non-Hispanic Whites. 

While children had the highest 

chronic poverty rate, adults 65 and 

over in poverty at the beginning 

of the 2004 Panel were the most 

likely to remain in poverty for the 

entire 3 years. About 38 percent of 

elderly adults in poverty in January 

and February 2004 were poor in all 

36 months while the comparable 

rates for children and working-age 

adults were 27.5 percent and 18.1 

percent, respectively. 

About 30 percent of people in 

female-householder families and 

unrelated individuals in poverty 

the first 2 months of the 2004 

Panel were poor all 36 months.17 

17 The estimate for people in femalehouseholder families was not statistically 

different from the estimate for unrelated 

individuals.

In contrast, about 11.3 percent of 

people in married-couple families 

in poverty in both January and 

February 2004 remained in poverty 

for all 36 months. The percentage of people in male-householder 

families remaining in poverty was 

not statistically different from the 

percentage for people in marriedcouple families.

Comparing the 2001 Panel with

the 2004 Panel, the percentage 

of people in a poverty spell at the 

beginning of the panel and poor 

for the subsequent 34 months 

increased from 20.0 percent to 

23.1 percent. This percentage 

increased for children, Blacks, 

and people in female-householder 

families. (The 2001 Panel rates can 

be found in Table A-5.) No other 

groups had this rate increase from 

the 2001 Panel to 2004 Panel.

Duration and Median Length

of Poverty Spells

Figure 9 shows the distribution of 

poverty spell lengths for the total 

population.18 Like the comparison 

between episodic and chronic 

poverty rates, the distribution of 

spells shows that most movements 

into poverty were short. Almost 

half of all spells (47.7 percent) 

lasted 4 months, 19.9 percent 

of spells lasted between 5 and 8 

months, and 9.2 percent of spells 

lasted between 9 and 12 months.19

Cumulatively, a little over 75 percent of all spells lasted less than 

1 year while 12.4 percent of all 

18 See the text box on page 2 for the 

definition of a poverty spell. An individual 

is counted more than once if he or she had 

multiple spells. Analysis excludes spells 

beginning on or before January 2004 (leftcensored spells) but includes spells ending 

on or after December 2006 (right-censored 

spells). See the Limitations on page 13 for a 

more detailed explanation of censored spells. 19 The percentage of spells lasting 9 to 

12 months (9.2 percent) was not statistically 

different from the percentage of spells lasting 

25 or more months (12.4 percent).

Figure 8.

People in Poverty in January and February 2004 

Who Were in Poverty All 36 Months by Selected 

Characteristics: 2004–2006

Note: Federal surveys, including the SIPP 2004 Panel, give respondents the option of 

reporting more than one race. These data can be shown in two ways (1) as mutually 

exclusive from other race groups, which may be denoted by "alone" or (2) not mutually 

exclusive with other race groups, denoted by "alone or in combination with other race 

groups." This figure shows race using the first method. Because Hispanics may be of 

any race, data for Hispanics are not mutually exclusive with race. Female householders 

have no husband present and male householders have no wife present. 

Source: U.S. Census Bureau, Survey of Income and Program Participation, 2004 Panel.

For information on confidentiality protection and sampling and nonsampling error,

see <http://www.census.gov/sipp/source.html>.

Percent

0 5 10 15 20 25 30 35 40

Unrelated individuals

Male-householder families

Female-householder families

Married-couple families

65 years and over

18 to 64 years

Under 18 years

Non-Hispanic

Hispanic

Black alone

White alone, non-Hispanic

White alone

All people
U.S. Census Bureau 11

poverty spells continued more than 

2 years.20

Figure 10 presents median spell 

lengths by demographic characteristics measured at the beginning 

of each spell. Median poverty spell 

length is the point in the distribution at which half of all spells are 

shorter and half of all spells are 

longer. For 2004 to 2006, consistent with the estimate that almost 

half of all poverty spells lasted less 

than 4 months, the median length 

of a poverty spell for the overall 

population was 4.5 months.21

Generally, the same groups that 

had higher episodic and chronic 

poverty rates had longer poverty 

spells. The length of poverty spells 

for different age groups followed a 

different pattern. Adults 65 years 

and over had a longer median 

poverty spell (6.7 months) than 

children (5.2 months) or adults 

18 to 64 years old (4.2 months). 

In contrast, children had higher 

chronic and episodic poverty rates 

than adults.

The median spell length for nonHispanic Whites (4.0 months) was 

shorter than median spell lengths 

for Hispanics and Blacks (6.2 

months and 5.9 months, respectively). Black and Hispanic poverty 

spell lengths were not statistically 

different from each other. 22

People in female-householder 

families had a longer median spell 

length (6.4 months) than people in 

other types of families. People in

20 If spells underway in January 2004 (leftcensored spells) are included in the analysis, 

the distribution shifts to the right: 40.9 (+/- 

1.2) percent of spells ended by 4 months, 

18.6 (+/- 0.9) percent lasted between 5 and 8 

months, 9.1 (+/-0.7) percent lasted between 9 

and 12 months, and 19.5 (+/- 0.9) percent of 

spells continued more than 24 months. 21 If spells underway in January 2004 

(left-censored spells) were included in the 

analysis then the median spell was 6.3 (+/- 

0.2) months. 22 Even after including left-censored spells, 

which included people in chronic poverty, the 

median poverty spell for Blacks (7.7 +/-0.6 

months) was not statistically different from 

the median poverty spell for Hispanics. 

Figure 9.

Duration of Poverty Spells: 2004–2006

Source: U.S. Census Bureau, Survey of Income and Program Participation, 2004 Panel. 

For information on confidentiality protection and sampling and nonsampling error,

see <http://www.census.gov/sipp/source.html>.

Percent of spells in interval, excludes spells 

underway in January 2004

0 10 20 30 40 50

25 months or more

21 to 24 months

17 to 20 months

13 to 16 months

9 to 12 months

5 to 8 months

2 to 4 months

Figure 10.

Median Length of Poverty Spells by Selected 

Characteristics: 2004–2006

Note: Federal surveys, including the SIPP 2004 Panel, give respondents the option of 

reporting more than one race. These data can be shown in two ways (1) as mutually 

exclusive from other race groups, which may be denoted by "alone" or (2) not mutually 

exclusive with other race groups, denoted by "alone or in combination with other race 

groups." This figure shows race using the first method. Because Hispanics may be of any 

race, data for Hispanics are not mutually exclusive with race. Female householders have 

no husband present and male householders have no wife present. 

Source: U.S. Census Bureau, Survey of Income and Program Participation, 2004 Panel.

For information on confidentiality protection and sampling and nonsampling error,

see <http://www.census.gov/sipp/source.html>.

Months, excludes spells 

underway in January 2004

0 1 2 3 4 5 6 7 8

Unrelated individuals

Male-householder families

Female-householder families

Married-couple families

65 years and over

18 to 64 years

Under 18 years

Not Hispanic

Hispanic

Black alone

White alone, not Hispanic

White alone

All people
12 U.S. Census Bureau

married-couple families had a 

shorter median spell length than 

other family types.23 

The median spell length increased 

for the overall population from 4.3 

to 4.5 months from the 2001 Panel 

to the 2004 Panel. It also increased 

for children from 4.4 months to 5.2 

months and for Hispanics from 4.8 

months to 6.2 months. It declined 

for unrelated individuals from 5.2 

months to 4.7 months. For all other 

demographic groups, median spell 

lengths in the first 36-month period 

of 2004 Panel were not different 

from those measured in the 2001 

Panel. (Estimates of spell lengths 

for the 2001 Panel can be found in 

Table A-7.)24

SUMMARY 

A comparison of poverty rates 

measured at varying intervals 

provides a complex picture of 

poverty. For most people who 

entered poverty, it was a transitory state rather than a permanent 

state and most poverty spells were 

short. During the 36 months from 

January 2004 to December 2006, 

28.9 percent of people experienced 

at least 1 poverty spell lasting at 

least 2 months (episodic poverty). 

About 2.8 percent of people had 

a poverty spell which lasted the 

full time period (chronic poverty). 

Almost half of all spells ended by 

4 months. However, among the 

people categorized as in a poverty 

spell at the beginning of the 2004 

Panel, almost 25 percent of people 

23 The median poverty spell length for 

unrelated individuals was also not statistically 

different from the median length of poverty 

spells for people in male-householder families 

(4.9 months). 24 The spell lengths for people in malehouseholder families were not calculated 

from 2001 to 2003 and therefore were not 

compared across panels. Cross-panel

comparisons in poverty measures of people

65 years and over should be done with

caution due to changes in collection and 

processing of social security income. A note 

at the end of this report discusses changes in 

the poverty measures for adults 65 and over 

between the 2001 and 2004 Panels. 

continued in poverty for the entire 

36 months studied. Most poverty 

spells were short, but 12.4 percent 

poverty spells lasted more than

2 years.25

The SIPP allows us to look at demographic differences in poverty risk 

for shorter and longer time periods. 

The pattern of poverty by race 

and Hispanic origin and age varied 

depending on the measure used. 

The episodic poverty rate for Blacks 

was not statistically different from 

the episodic poverty rate for Hispanics, but Blacks had a lower poverty exit rate and a higher chronic 

poverty rate than Hispanics. 

While CPS ASEC annual poverty 

rates have generally shown a 

decline in elderly poverty rates 

since the 1960s, the SIPP data

provide a more complex picture

of the dynamics of poverty for 

adults 65 years and over..

26 Adults 

65 years and over were least likely 

to be in poverty, but once poor, 

they were as likely to remain in 

poverty as children under 18 years, 

the age group most at risk to be 

in poverty. (The elderly were least 

likely to be poor for 2 or more 

months, but their poverty exit rate 

was not statistically different from 

that for children.)

All measures in this report show 

that people in female-householder 

families were more likely to be in 

poverty than people in marriedcouple families. People in femalehouseholder families also had 

25 This report does not address whether 

people have multiple spells of poverty and 

does not account for re-entry into poverty. 

See Ann Huff Stevens, “Climbing Out of

Poverty, Falling Back In: Measuring the

Persistence of Poverty Over Multiple Spells,” 

Journal of Human Resources 34 (1999),

pp. 557–588. 26 The CPS annual poverty rate for adults 

65 and over declined from 28.5 percent in 

1965 to 9.7 percent in 2008. From Carmen 

DeNavas-Walt, Bernadette D. Proctor, and 

Jessica C. Smith, “Income, Poverty and Health 

Insurance Coverage in the United States: 

2008,” Current Population Reports, Series 

P60-236, U.S. Census Bureau, Washington, DC. 

longer poverty spells and those 

experiencing a poverty spell at the 

beginning of the 2004 Panel were 

the most likely to remain in poverty 

for the entire period.

SIPP data from the 2001 and the 

2004 Panels paint a picture of poverty for the period which coincided 

with the economic expansion that 

started in November 2001 and 

ended in December 2007.27 Over 

this period, the episodic poverty 

rate declined for almost all demographic groups but the chronic 

poverty rate increased for the 

overall population and for several 

subpopulations. The median length 

of a poverty spell increased for the 

overall population and for children 

and Hispanics. 

SOURCE OF DATA

The population represented (the 

population universe) in the 2001 

and 2004 Survey of Income and 

Program Participation (SIPP) panels 

is the civilian noninstitutionalized 

population living in the United 

States. The SIPP is a longitudinal 

survey conducted at 4-month

intervals. The data in this report 

reference January 2001 through 

December 2003 and January 2004 

to December 2006. For the 2001 

SIPP panel, approximately 50,500 

housing units were in the sample 

for the first wave. Of the 40,500 

eligible units, 35,000 were interviewed. For the 2004 SIPP panel, 

approximately 62,700 housing 

units were in sample for the first 

wave. Of the 51,400 eligible units, 

43,700 were interviewed. The 

institutionalized population, which 

is excluded from the population 

universe, is composed primarily

of the population in correctional 

institutions and nursing homes 

27 Recessions are defined by the National 

Bureau of Economic Research (NBER). A 

trough occurred in November 2001 and a 

peak occurred in December 2007. For more 

information, see <http://www.nber.org

/cycles/cyclesmain.html>.
U.S. Census Bureau 13

(91.0 percent of the 4.1 million 

institutionalized people in Census 

2000).

ACCURACY OF ESTIMATES

Statistics from surveys are subject 

to sampling and nonsampling error. 

All comparisons presented in this 

report have taken sampling error 

into account and are significant 

at the 90 percent confidence level 

unless otherwise noted. This means 

the 90 percent confidence interval for the difference between the 

estimates being compared does not 

include zero. Nonsampling errors 

in surveys may be attributed to a 

variety of sources, such as how the 

survey is designed, how respondents interpret questions, how 

able and willing respondents are to 

provide correct answers, and how 

accurately the answers are coded 

and classified. The U.S. Census 

Bureau employs quality control 

procedures throughout the production process including the overall 

design of surveys, the wording of 

questions, review of the work of 

interviewers and coders, and the 

statistical review of reports to minimize these errors. The SIPP weighting procedure uses ratio estimation, whereby sample estimates are 

adjusted to independent estimates 

of the national population by age, 

race, sex, and Hispanic origin. This 

weighting partially corrects for bias 

due to undercoverage, but biases 

may still be present when people 

who are missed by the survey 

differ from those interviewed in 

ways other than age, race, sex, and 

Hispanic origin. How this weighting 

procedure affects other variables in 

the survey is not precisely known. 

All of these considerations affect 

comparisons across different surveys or data sources.

For further information on statistical standards and the computation 

and use of standard errors, go to 

<http://www.census.gov/sipp

/sourceac/S&A04_1toW12(S&A-10)

.pdf > (2004 Panel) and 

<http://www.census.gov/sipp

/sourceac/S&A01_20060323

_Long(S&A-3).pdf > (2001 Panel)

or contact Sarah Tekansik of the

Census Bureau’s Demographic

Statistical Methods Division at

<sarah.tekansik@census.gov>

or 301-763-1860. For more

information about the content

of this report, contact Robin J. 

Anderson, Poverty Statistics Branch, 

at <robin.j.anderson@census.gov> 

or 301-763-5996. Additional information on the SIPP can be found at 

the following Web sites:

<www.sipp.census.gov

/sipp/> (main SIPP Web site),

<http://www.census.gov/sipp

/workpapr/wp230.pdf >

(SIPP Quality Profile), and

<http://www.census.gov/sipp

/usrguide.html> (SIPP Users’ Guide).

LIMITATIONS

Nonsampling Errors

All surveys have potential sampling 

and nonsampling error. Additionally, longitudinal surveys may have 

both seam and attrition biases. 

The seam phenomenon occurs 

when respondents report the same 

status of monthly variables within 

waves. If seam bias is present then 

monthly variables are more likely 

to change in on-seam months 

(months of different waves) than 

off-seam months (months within 

the same wave). Attrition bias may 

occur if respondents leaving the 

survey are systematically different 

from those who stay in the survey.

The household sample loss rate 

in the 2004 SIPP was 15 percent 

in wave 1 and 37 percent in wave 

12. In the SIPP, the Census Bureau 

uses a combination of weighting 

and imputation methods to reduce 

the bias of nonresponse on three 

levels (household, person, and item 

nonresponse levels). The effectiveness of those procedures remains

a matter of ongoing research.28

Longitudinal Editing and 

Longitudinal Analysis

In the 2001 Panel, selected demographic and household characteristics from early waves were used 

in the entire panel.29 In the 2004 

Panel, reported characteristics were 

used, even if they varied from 

initial reports. A small number of 

observations had varying sex, 

race, and Hispanic origin across 

the panel. Of those people in the 

3-year panel with a valid interview 

status in the poverty universe for 

all 36 months, less than 1 percent 

of all observations had race, sex, or 

Hispanic origin that varied across 

waves. Using weighted estimates, 

2.3 million people had race vary by 

wave; about 300,000 people had sex 

vary by wave; and 1.6 million people 

had Hispanic origin vary by wave. 

This report has certain sample 

restrictions and makes certain 

assumptions about the stability of 

demographic characteristics across 

the panel. The analyses in this 

report measure poverty across calendar years 2001 to 2006 and from 

3-year periods from January 2001 

to December 2003 and January 

2004 to December 2006. For each 

time period, analyses include only 

respondents with a valid weight 

and who are within the poverty 

universe for the entire period.30

The poverty universe excludes 

unrelated children 14 years

28 U.S. Census Bureau, Survey of Income 

and Program Participation Users’ Guide, 

update, pp. 6-2–6-5, 2008, 

<http://www.census.gov/sipp/usrguide

/chap6rev2008.pdf>. 29 U.S. Census Bureau, Survey of Income 

and Program Participation Users’ Guide, 

update, p. 4-19, 2009, <http://www.census

.gov/sipp/usrguide/chap4rev2009.pdf>. 30 For more details, see the Source and 

Accuracy Statements: <http://www.census

.gov/sipp/sourceac/S&A04_W1toW12(S&A-10)

.pdf> and <http://www.census.gov/sipp

/sourceac/S&A01_20060323_Long(S&A-3)

.pdf>.
14 U.S. Census Bureau

or younger. Demographic characteristics are held constant to values 

reported at the beginning of the 

relevant time period. 

Censoring and Spell Analysis

The text box on page 2 describes 

the definition of poverty spells 

used in this report. Poverty spells 

may be left or right-censored. An 

individual’s poverty spell may be 

in progress before January 2004 

(left-censored) or in progress in 

December 2006 (right-censored). 

This analysis used the life table 

method in the SAS software to 

include right-censored spells in the 

estimates of median spell lengths 

and the duration of poverty spells. 

The life table method assumes 

right-censored spells are censored 

at the midpoint of each interval 

and the effective sample size of 

each interval includes only half of 

the right-censored spells included 

in the interval. The analysis in 

this report excludes left-censored 

spells, since the start time for these 

spells cannot be determined and 

few statistical programs and methods have been developed to correct 

for left censoring.31 Approximately 

28 percent of poverty spells were 

left-censored. By excluding left-censored spells, systematic bias may 

be introduced into the median spell 

and duration analyses.32

31 See Paul D Allison, Survival Analysis 

Using the SAS System: A Practical Guide, Cary, 

N.C: SAS Inc, 1995, p. 292. 32 A variety of papers discuss how left censoring may bias duration analysis and suggest potential corrections. Guang Guo, “Event 

History Analysis and Left-Truncated Data,” in 

P. Marsden (Ed.), Sociological Methodology, 

Vol. 23, Jossey-Bass, San Francisco, CA,1993, 

pp. 217–242. David W. Hosmer and Stanley 

Lemeshow, Applied Survival Analysis: 

Regression Modeling of Time to Event Data, 

Wiley, New York, 1999. John Iceland, “The 

Dynamics of Poverty Spells and Issues of Left 

Censoring,” PCS Research Report, Series:

No. 97-378, 1997. 

Changes in the Reporting and 

Processing of Social Security 

Income in the 2004 Panel

The Census Bureau changed the 

way it collected and edited social 

security income between the 2001 

and 2004 SIPP Panels. Users should 

use caution when comparing 2001 

and 2004 poverty rates for adults 

65 years and over. For most social 

security recipients (those 65 and 

over or disabled), Medicare Part 

B premiums are deducted by the 

Social Security Administration from 

their monthly payments. In the 

2001 Panel, SIPP collected social 

security amounts net of Medicare 

Part B premiums but did not adjust 

social security income to obtain 

an estimate of gross social security income. In the 2004 Panel, the 

instrument was designed to collect 

Medicare Part B premium amounts 

so that they could be added to net 

social security income to calculate 

gross social security income. However, there were errors in both the 

instrument and the processing of 

social security data in the 2004 Panel. 

In order to correct for the instrument errors, the social security 

data were re-edited to randomly 

assign a fixed Medicare Part B 

premium amount to respondents 

in the universe (65 years and over 

or disabled). The allocation rule 

was implemented for each wave 

independent of the prior wave 

response. This resulted in some 

individuals being allocated a Part B 

Premium in one wave but not necessarily being allocated a premium 

amount in preceding or subsequent 

waves. Over the 48-month duration 

of the 2004 SIPP panel, monthly 

social security amounts for some 

individuals, families, and households may fluctuate by the fixed 

dollar amount of the Medicare Part 

B premium.33

USER COMMENTS

The U.S. Census Bureau welcomes 

comments and advice of data and 

report users. If you have any suggestions or comments on income 

and poverty data, please write to:

Charles T. Nelson,

Assistant Division Chief,

Economic Characteristics,

Housing and Household

Economic Statistics Division,

U.S. Census Bureau,

Washington, DC 20233-8500

or send e-mail to 

<charles.t.nelson@census.gov>.

SUGGESTED CITATION

Anderson, Robin J., “Dynamics 

of Economic Well-being: Poverty, 

2004–2006.” Current Population 

Reports, P70-123, U.S. Census 

Bureau, Washington, DC, 2011.

33 From the SIPP 2004 Panel General 

Income User Note 10, see

<http://www.census.gov/sipp/core_content

/core_notes/2004General_Income.html>.
U.S. Census Bureau 15 APPENDIX Table A-1. People in Poverty 2 or More Months by Selected Characteristics: 2001–2003 (Numbers in thousands) Characteristic 3-year panel (2001–2003) 1 2001 1 2002 1 2003 1 Total People in poverty 2 or more months Total People in poverty 2 or more months Total People in poverty 2 or more months Total People in poverty 2 or more months Number Percent Number Percent Number Percent Number Percent Esti- mate 90 per- cent C.I. 2 (+/-) Esti- mate 90 per- cent C.I. 2 (+/-) Esti- mate 90 per- cent C.I. 2 (+/-) Esti- mate 90 per- cent C.I. 2 (+/-) Esti- mate 90 per- cent C.I. 2 (+/-) Esti- mate 90 per- cent C.I. 2 (+/-) Esti- mate 90 per- cent C.I. 2 (+/-) Esti- mate 90 per- cent C.I. 2 (+/-) All people . . . . . . . . . . . . . 264,555 85,497 1,139 32.3 0.5 273,967 61,971 932 22.6 0.4 275,789 60,285 1,052 21.9 0.4 280,421 57,476 1,002 20.5 0.4 Race and Hispanic Origin White 3. . . . . . . . . . . . . . . . . 216,399 63,457 1,059 29.3 0.5 224,549 44,876 835 20.0 0.4 225,500 43,177 937 19.1 0.4 229,271 41,433 891 18.1 0.4 White, non-Hispanic 4. . . . 187,249 49,300 975 26.3 0.5 193,274 33,462 744 17.3 0.4 193,202 32,116 832 16.6 0.4 194,637 30,388 786 15.6 0.4 Black 3. . . . . . . . . . . . . . . . . 33,661 16,978 476 50.4 1.4 34,754 13,504 382 38.9 1.1 35,232 13,292 441 37.7 1.3 35,931 12,521 439 34.8 1.2 Hispanic 4 . . . . . . . . . . . . . . 31,934 15,608 456 48.9 1.7 34,338 12,539 431 36.5 1.4 35,641 12,391 443 34.8 1.4 37,963 12,350 480 32.5 1.4 Non-Hispanic. . . . . . . . . . . . 232,621 69,889 1,089 30.0 0.5 239,629 49,432 865 20.6 0.4 240,148 47,895 973 19.9 0.4 242,457 45,126 920 18.6 0.4 Age Under 18 years. . . . . . . . . . 69,971 28,428 785 40.6 0.9 71,434 21,459 615 30.0 0.8 71,394 20,921 691 29.3 0.9 71,477 20,297 658 28.4 0.8 18 to 64 years. . . . . . . . . . . 165,299 50,144 981 30.3 0.6 170,139 35,015 758 20.6 0.4 172,106 34,407 856 20.0 0.5 176,147 32,597 809 18.5 0.4 65 years and over. . . . . . . . 29,285 6,925 409 23.6 1.2 32,394 5,496 324 17.0 0.9 32,289 4,957 350 15.4 1.0 32,797 4,582 325 14.0 0.9 Family status In married-couple families. . 175,883 42,254 922 24.0 0.5 179,538 26,220 672 14.6 0.4 180,833 25,885 760 14.3 0.4 183,835 25,038 723 13.6 0.4 In families with a female householder, no husband present . . . . . . . . . . . . . . . 37,715 21,348 693 56.6 1.3 39,445 18,267 572 46.3 1.1 40,516 17,791 643 43.9 1.2 42,232 17,440 615 41.3 1.2 In families with a male householder, no wife present . . . . . . . . . . . . . . . 10,726 4,333 325 40.4 2.4 11,813 2,928 238 24.8 1.8 10,961 2,757 262 25.2 2.1 11,346 2,610 246 23.0 1.9 Unrelated individuals. . . . . . 40,231 17,562 634 43.7 1.2 43,171 14,556 515 33.7 1.0 43,479 13,852 572 31.9 1.1 43,008 12,388 524 28.8 1.1 1 Panel and yearly estimates are based on different samples. The 3-year panel estimates include only respondents in the panel for 9 waves, whereas calendar year estimates include respondents in the sample for 12 months. The total number of respondents in each sample are as follows: 47,246 in the 3-year panel; 61,527 in 2001; 57,203 in 2002; and 57,903 in 2003. 2 A 90 percent confidence interval (C.I.) is a measure of an estimate’s variability. The larger the confidence interval in relation to the size of the estimate, the less reliable the estimate. 3 Federal surveys, including the SIPP 2004 Panel, give respondents the option of reporting more than one race. These data can be shown in two ways: (1) as mutually exclusive from other race groups, which may be denoted by “alone” or (2) not mutually exclusive with other race groups, denoted by “alone or in combination with other race groups.” The figures, tables, and text in this report show race using the first method. The SIPP 2001 Panel did not allow respondents to report more than one race. 4 Hispanics may be any race, data in this report for Hispanics overlap data for racial groups. Data users should exercise caution when interpreting aggregate results for these groups because they consist of many distinct subgroups that differ in socioeconomic characteristics, culture, and recency of immigration. Source: U.S. Census Bureau, Survey of Income and Program Participation, 2001 Panel. For information on confidentiality protection and sampling and nonsampling error, see <http://www.census.gov /sipp/source.html>.
16 U.S. Census Bureau Table A-2. People in Poverty 2 or More Months by Selected Characteristics: 2004–2006 (Numbers in thousands) Characteristic 3-year panel (2004–2006) 1 2004 1 2005 1 2006 1 People in poverty 2 or more months People in poverty 2 or more months People in poverty 2 or more months People in poverty 2 or more months Number Percent Number Percent Number Percent Number Percent Total Esti- mate 90 per- cent C.I. 2 (+/-) Esti- mate 90 per- cent C.I. 2 (+/-) Total Esti- mate 90 per- cent C.I. 2 (+/-) Esti- mate 90 per- cent C.I. 2 (+/-) Total Num- ber 90 per- cent C.I. 2 (+/-) Per- cent 90 per- cent C.I. 2 (+/-) Total Num- ber 90 per- cent C.I. 2 (+/-) Per- cent 90 per- cent C.I. 2 (+/-) All people . . . . . . . . . 270,914 78,348 1,361 28.9 0.5 281,963 59,203 749 21.0 0.3 285,073 57,780 807 20.3 0.3 287,299 55,824 1,162 19.4 0.4 Race and Hispanic Origin White alone 3. . . . . . . . 218,713 56,837 1,232 26.0 0.6 227,517 42,141 660 18.5 0.3 229,484 41,197 710 18.0 0.3 231,210 39,479 1,017 17.1 0.4 White alone, non-Hispanic 4. . . . . 185,708 41,945 1,100 22.6 0.6 191,669 29,985 573 15.6 0.3 192,263 29,182 614 15.2 0.3 192,755 27,142 867 14.1 0.4 Black alone 3. . . . . . . . 33,773 15,373 617 45.5 1.7 35,325 12,458 331 35.3 0.9 35,751 12,027 357 33.6 0.9 35,828 11,883 531 33.2 1.4 Hispanic 4. . . . . . . . . . . 36,043 16,491 665 45.8 1.7 38,776 13,254 410 34.2 1.0 40,269 13,075 453 32.5 1.1 41,733 13,346 624 32.0 1.4 Non-Hispanic. . . . . . . . 234,871 61,858 1,268 26.3 0.5 243,187 45,949 683 18.9 0.3 244,804 44,705 733 18.3 0.3 245,566 42,478 1,048 17.3 0.4 Age Under 18 years. . . . . . 70,579 25,684 895 36.4 1.1 71,948 20,076 479 27.9 0.6 72,432 19,973 518 27.6 0.6 72,373 19,211 742 26.5 0.9 18 to 64 years. . . . . . . 170,610 47,286 1,152 27.7 0.6 176,821 35,024 612 19.8 0.3 179,194 34,003 656 19.0 0.4 181,298 32,688 940 18.0 0.5 65 years and over. . . . 29,725 5,378 428 18.1 1.3 33,193 4,103 224 12.4 0.6 33,447 3,805 234 11.4 0.7 33,628 3,926 346 11.7 1.0 Family status In married-couple families. . . . . . . . . . . 178,576 37,355 1,050 20.9 0.6 182,750 24,350 523 13.3 0.3 184,694 24,339 567 13.2 0.3 186,228 22,847 803 12.3 0.4 In families with a female householder, no hus- band present . . . . . . 39,035 20,218 804 51.8 1.5 41,933 17,628 451 42.0 0.8 42,804 17,584 489 41.1 0.9 42,781 17,478 711 40.9 1.3 In families with a male householder, no wife present . . . . . . . . . . . 11,068 4,129 376 37.3 2.7 12,059 3,371 203 28.0 1.4 11,981 2,906 205 24.3 1.5 11,849 2,544 280 21.5 2.1 Unrelated individuals. . 42,235 16,647 735 39.4 1.4 45,221 13,854 403 30.6 0.8 45,594 12,952 424 28.4 0.8 46,442 12,955 618 27.9 1.2 1 Panel and yearly estimates are based on different samples. The 3-year panel estimates include only respondents in the panel for 10 waves, whereas calendar year estimates include respondents in the sample for 12 months. The numbers of respondents in each sample are as follows: 27,840 in the 3 year panel; 86,128 in 2004; 76,953 in 2005; and 34,372 in 2006. In wave 9 of the SIPP 2004 Panel, a 53 percent sample reduction was made. However, the calendar year weight for 2006 and the 3-year panel weight correct for that sample reduction. 2 A 90 percent confidence interval (C.I.) is a measure of an estimate’s variability. The larger the confidence interval in relation to the size of the estimate, the less reliable the estimate. 3 Federal surveys, including the SIPP 2004 Panel, give respondents the option of reporting more than one race. These data can be shown in two ways: (1) as mutually exclusive from other race groups, which may be denoted by “alone” or (2) not mutually exclusive with other race groups, denoted by “alone or in combination with other race groups.” The figures, tables, and text in this report show race using the first method. 4 Hispanics may be any race, data in this report for Hispanics overlap data for racial groups. Data users should exercise caution when interpreting aggregate results for these groups because they consist of many distinct subgroups that differ in socioeconomic characteristics, culture, and recency of immigration. Source: U.S. Census Bureau, Survey of Income and Program Participation, 2004 Panel. For information on confidentiality protection and sampling and nonsampling error, see <http://www.census.gov/sipp /source.html>.
U.S. Census Bureau 17

Table A-3.

People in Poverty All 36 Months by Selected Characteristics: 2001–2003

(Numbers in thousands)

Characteristic

3-year panel (2001–2003)

Total

People in poverty all 36 months

Number Percent

Estimate

90 percent

C.I. 1 (+/-) Estimate

90 percent

C.I. 1 (+/-)

All people . . . . . . . . . . . . . . . . . . . . . . . 264,555 6,250 389 2.4 0.1

Race and Hispanic Origin

White 2. . . . . . . . . . . . . . . . . . . . . . . . . . . 216,399 3,576 296 1.7 0.1

 White, non-Hispanic 3. . . . . . . . . . . . . . 187,249 2,502 248 1.3 0.1

Black 2. . . . . . . . . . . . . . . . . . . . . . . . . . . 33,661 2,226 234 6.6 0.7

Hispanic 3. . . . . . . . . . . . . . . . . . . . . . . . . 31,934 1,210 173 3.8 0.5

Non-Hispanic. . . . . . . . . . . . . . . . . . . . . . 232,621 5,040 350 2.2 0.2

Age

Under 18 years. . . . . . . . . . . . . . . . . . . . 69,971 2,227 234 3.2 0.3

18 to 64 years. . . . . . . . . . . . . . . . . . . . . 165,299 2,915 268 1.8 0.2

65 years and over. . . . . . . . . . . . . . . . . . 29,285 1,108 166 3.8 0.6

Family status

In married-couple families. . . . . . . . . . . . 175,883 1,097 165 0.6 0.1

In families with a female householder,

 no husband present. . . . . . . . . . . . . . . . 37,715 2,558 251 6.8 0.6

In families with a male householder,

 no wife present. . . . . . . . . . . . . . . . . . . 10,726 118 54 1.1 0.5

Unrelated individuals. . . . . . . . . . . . . . . . 40,231 2,477 247 6.2 0.6

1 A 90 percent confidence interval (C.I.) is a measure of an estimate’s variability. The larger the confidence interval in relation to the size of the 

estimate, the less reliable the estimate.

2 Federal surveys, including the SIPP 2004 Panel, give respondents the option of reporting more than one race. These data can be shown in 

two ways: (1) as mutually exclusive from other race groups, which may be denoted by “alone” or (2) not mutually exclusive with other race groups, 

denoted by “alone or in combination with other race groups.” The figures, tables, and text in this report show race using the first method. The SIPP 

2001 Panel did not allow respondents to report more than one race.

3 Hispanics may be any race, data in this report for Hispanics overlap data for racial groups. Data users should exercise caution when interpreting aggregate results for these groups because they consist of many distinct subgroups that differ in socioeconomic characteristics, culture, and 

recency of immigration.

Source: U.S. Census Bureau, Survey of Income and Program Participation, 2001 Panel. For information on confidentiality protection and sampling 

and nonsampling error, see <http://www.census.gov/sipp/source.html>.
18 U.S. Census Bureau

Table A-4.

People in Poverty All 36 Months by Selected Characteristics: 2004–2006

(Numbers in thousands)

Characteristic

3-year panel (2004–2006)

Total

People in poverty all 36 months

Number Percent

Estimate

90 percent 

C.I. 1 (+/-) Estimate

90 percent

C.I. 1 (+/-)

All people . . . . . . . . . . . . . . . . . . . . . . . 270,914 7,554 505 2.8 0.2

Race and Hispanic Origin

White alone 2. . . . . . . . . . . . . . . . . . . . . . 218,713 4,116 375 1.9 0.2

 White alone, non-Hispanic 3. . . . . . . . . . 185,708 2,590 299 1.4 0.2

Black alone 2. . . . . . . . . . . . . . . . . . . . . . 33,773 2,838 317 8.4 0.9

Hispanic 3. . . . . . . . . . . . . . . . . . . . . . . . . 36,043 1,619 252 4.5 0.7

Non-Hispanic. . . . . . . . . . . . . . . . . . . . . . 234,871 5,935 449 2.5 0.2

Age

Under 18 years. . . . . . . . . . . . . . . . . . . . 70,579 3,388 341 4.8 0.5

18 to 64 years. . . . . . . . . . . . . . . . . . . . . 170,610 3,273 335 1.9 0.2

65 years and over. . . . . . . . . . . . . . . . . . 29,725 893 176 3.0 0.6

Family status

In married-couple families. . . . . . . . . . . . 178,576 1,283 211 0.7 0.1

In families with a female householder,

 no husband present . . . . . . . . . . . . . . . 39,035 3,772 360 9.7 0.9

In families with a male householder,

 no wife present . . . . . . . . . . . . . . . . . . . 11,068 290 100 2.6 0.9

Unrelated individuals. . . . . . . . . . . . . . . . 42,235 2,209 276 5.2 0.6

1 A 90 percent confidence interval (C.I.) is a measure of an estimate’s variability. The larger the confidence interval in relation to the size of the 

estimate, the less reliable the estimate.

2 Federal surveys, including the SIPP 2004 Panel, give respondents the option of reporting more than one race. These data can be shown in 

two ways: (1) as mutually exclusive from other race groups, which may be denoted by “alone” or (2) not mutually exclusive with other race groups, 

denoted by “alone or in combination with other race groups.” The figures, tables, and text in this report show race using the first method. 

3 Hispanics may be any race, data in this report for Hispanics overlap data for racial groups. Data users should exercise caution when interpreting aggregate results for these groups because they consist of many distinct subgroups that differ in socioeconomic characteristics, culture, and 

recency of immigration.

Source: U.S. Census Bureau, Survey of Income and Program Participation, 2004 Panel. For information on confidentiality protection and sampling 

and nonsampling error, see <http://www.census.gov/sipp/source.html>.
U.S. Census Bureau 19

Table A-5.

People in Poverty in All 36 Months as a Percentage of Those in Poverty the First 2 Months 

by Selected Characteristics: 2001–2003

(Numbers in thousands) 

Characteristic

People in poverty in January and February 2001 1

Total

People in poverty all 36 months,

2001–2003

Number Number Percent

Estimate

90 percent

C.I. 2 (+/-) Estimate

90 percent

C.I. 2 (+/-) Estimate

90 percent

C.I. 2 (+/-)

All people . . . . . . . . . . . . . . . . . . . . . . . 31,296 883 6,250 389 20.0 1.1

Race and Hispanic Origin

White 3. . . . . . . . . . . . . . . . . . . . . . . . . . . 21,471 732 3,576 296 16.7 1.3

 White, non-Hispanic 4. . . . . . . . . . . . . . 15,515 622 2,502 248 16.1 1.5

Black 3. . . . . . . . . . . . . . . . . . . . . . . . . . . 7,824 451 2,226 234 28.4 2.6

Hispanic 4. . . . . . . . . . . . . . . . . . . . . . . . . 6,620 483 1,210 173 18.3 2.8

Non-Hispanic. . . . . . . . . . . . . . . . . . . . . . 24,675 784 5,040 350 20.4 1.3

Age

Under 18 years. . . . . . . . . . . . . . . . . . . . 11,371 532 2,227 234 19.6 1.9

18 to 64 years. . . . . . . . . . . . . . . . . . . . . 16,993 651 2,915 268 17.2 1.4

65 years and over. . . . . . . . . . . . . . . . . . 2,931 270 1,108 166 37.8 4.5

Family status

In married-couple families. . . . . . . . . . . . 10,999 524 1,097 165 10.0 1.4

In families with a female householder,

 no husband present . . . . . . . . . . . . . . . 11,126 527 2,558 251 23.0 2.0

In families with a male householder,

 no wife present . . . . . . . . . . . . . . . . . . . 1,121 167 118 54 10.5 4.6

Unrelated individuals. . . . . . . . . . . . . . . . 8,050 448 2,477 247 30.8 2.6

1 Uses panel weight. 

2 A 90 percent confidence interval (C.I.) is a measure of an estimate’s variability. The larger the confidence interval in relation to the size of the 

estimate, the less reliable the estimate. 

3 Federal surveys, including the SIPP 2004 Panel, give respondents the option of reporting more than one race. These data can be shown in 

two ways: (1) as mutually exclusive from other race groups, which may be denoted by “alone” or (2) not mutually exclusive with other race groups, 

denoted by “alone or in combination with other race groups.” The figures, tables, and text in this report show race using the first method. The SIPP 

2001 Panel did not allow respondents to report more than one race. 

4 Hispanics may be any race, data in this report for Hispanics overlap data for racial groups. Data users should exercise caution when interpreting aggregate results for these groups because they consist of many distinct subgroups that differ in socioeconomic characteristics, culture, and 

recency of immigration.

Source: U.S. Census Bureau, Survey of Income and Program Participation, 2001 Panel. For information on confidentiality protection and sampling 

and nonsampling error, see <http://www.census.gov/sipp/source.html>.
20 U.S. Census Bureau

Table A-6.

People in Poverty in All 36 Months as a Percentage of Those in Poverty in the First 2 

Months by Selected Characteristics: 2004–2006 

(Numbers in thousands) 

Characteristic

People in poverty in January and February 2004 1

Total

People in poverty all 36 months,

2004–2006

Number Number Percent

Estimate

90 percent

C.I. 2 (+/-) Estimate

90 percent

C.I 2 (+/-) Estimate

90 percent

C.I. 2 (+/-)

All people . . . . . . . . . . . . . . . . . . . . . . . 32,747 1,068 7,554 505 23.1 1.4

Race and Hispanic Origin

White alone 3. . . . . . . . . . . . . . . . . . . . . . 21,659 869 4,116 375 19.0 1.6

 White alone, non-Hispanic 4. . . . . . . . . . 14,417 709 2,590 299 18.0 1.9

Black alone 3. . . . . . . . . . . . . . . . . . . . . . 8,485 566 2,838 317 33.4 3.1

Hispanic 4. . . . . . . . . . . . . . . . . . . . . . . . . 7,918 566 1,619 252 20.4 2.9

Non-Hispanic. . . . . . . . . . . . . . . . . . . . . . 24,829 930 5,935 449 23.9 1.6

Age

Under 18 years. . . . . . . . . . . . . . . . . . . . 12,331 655 3,388 341 27.5 2.4

18 to 64 years. . . . . . . . . . . . . . . . . . . . . 18,060 793 3,273 335 18.1 1.7

65 years and over. . . . . . . . . . . . . . . . . . 2,356 286 893 176 37.9 5.9

Family status

In married-couple families. . . . . . . . . . . . 11,311 628 1,283 211 11.3 1.8

In families with a female householder,

 no husband present . . . . . . . . . . . . . . . 11,936 645 3,772 360 31.6 2.5

In families with a male householder,

 no wife present . . . . . . . . . . . . . . . . . . . 1,738 246 290 100 16.7 5.3

Unrelated individuals. . . . . . . . . . . . . . . . 7,762 520 2,209 276 28.5 3.0

1

 Uses panel weight. 

2

 A 90 percent confidence interval (C.I.) is a measure of an estimate’s variability. The larger the confidence interval in relation to the size of the estimate,

the less reliable the estimate. 

3

 Federal surveys, including the SIPP 2004 Panel, give respondents the option of reporting more than one race. These data can be shown in two ways:

(1) as mutually exclusive from other race groups, which may be denoted by “alone” or (2) not mutually exclusive with other race groups, denoted by “alone or

in combination with other race groups.” The figures, tables, and text in this report show race using the first method. 

4

 Hispanics may be any race, data in this report for Hispanics overlap data for racial groups. Data users should exercise caution when interpreting aggregate 

results for these groups because they consist of many distinct subgroups that differ in socioeconomic characteristics, culture, and recency of immigration.

Source: U.S. Census Bureau, Survey of Income and Program Participation, 2004 Panel. For information on confidentiality protection and sampling and

nonsampling error, see <http://www.census.gov/sipp/source.html>.
U.S. Census Bureau 21

Table A-7.

Median Length of Poverty Spells by 

Selected Characteristics: 2001–2003

(In months, excluding spells underway in January 2001)

Characteristic

Median 

spell 

length 

(months)

90 percent 

C.I. 1 (+/-)

All people . . . . . . . . . . . . . . . . . . . . . . . . 4.3 0.2

Race and Hispanic Origin

White 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.0 0.2

 White, not Hispanic 3. . . . . . . . . . . . . . . . 3.9 0.2

Black 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.0 0.4

Hispanic 3. . . . . . . . . . . . . . . . . . . . . . . . . . 4.8 0.4

Not Hispanic. . . . . . . . . . . . . . . . . . . . . . . 4.1 0.1

Age

Under 18 years. . . . . . . . . . . . . . . . . . . . . 4.4 0.3

18 to 64 years. . . . . . . . . . . . . . . . . . . . . . 4.1 0.2

65 years and over. . . . . . . . . . . . . . . . . . . 5.8 0.5

Family status

In married-couple families. . . . . . . . . . . . . 3.9 0.1

In families with a female householder,

 no husband present . . . . . . . . . . . . . . . . 5.8 0.6

Unrelated individuals. . . . . . . . . . . . . . . . . 5.2 0.3

1

 A 90 percent confidence interval (C.I.) is a measure of an estimate’s 

variability. The larger the confidence interval in relation to the size of the 

estimate, the less reliable the estimate.

2

 Federal surveys, including the SIPP 2004 Panel, give respondents 

the option of reporting more than one race. These data can be shown to 

in two ways: (1) as mutually exclusive from other race groups, which may 

be denoted by “alone” or (2) not mutually exclusive with other race groups, 

denoted by “alone or in combination with other race groups.” The figures,

tables, and text in this report show race using the first method. The SIPP 

2001 Panel did not allow respondents to report more than one race.

3

 Hispanics may be any race, data in this report for Hispanics overlap 

data for racial groups. Data users should exercise caution when interpreting aggregate results for these groups because they consist of many distinct 

subgroups that differ in socioeconomic characteristics, culture, and recency 

of immigration.

Source: U.S. Census Bureau, Survey of Income and Program 

Participation, 2001 Panel. For information on confidentiality protection

and sampling and nonsampling error, see <http://www.census.gov/sipp

/source.html>.

Table A-8.

Median Length of Poverty Spells by 

Selected Characteristics: 2004–2006

(In months, excluding spells underway in January 2004)

Characteristic

Median 

spell 

length 

(months)

90 percent 

C.I. 1 (+/-)

All people . . . . . . . . . . . . . . . . . . . . . . . . 4.5 0.2

Race and Hispanic Origin

White alone 2. . . . . . . . . . . . . . . . . . . . . . . 4.3 0.2

 White alone, non-Hispanic 3. . . . . . . . . . . 4.0 0.2

Black alone 2. . . . . . . . . . . . . . . . . . . . . . . 5.9 0.5

Hispanic 3. . . . . . . . . . . . . . . . . . . . . . . . . . 6.2 0.5

Non-Hispanic. . . . . . . . . . . . . . . . . . . . . . . 4.2 0.2

Age

Under 18 years. . . . . . . . . . . . . . . . . . . . . 5.2 0.3

18 to 64 years. . . . . . . . . . . . . . . . . . . . . . 4.2 0.2

65 years and over. . . . . . . . . . . . . . . . . . . 6.7 0.8

Family status

In married-couple families. . . . . . . . . . . . . 3.9 0.2

In families with a female householder,

 no husband present. . . . . . . . . . . . . . . . . 6.4 0.4

In families with a male householder,

 no wife present. . . . . . . . . . . . . . . . . . . . 4.9 0.8

Unrelated individuals. . . . . . . . . . . . . . . . . 4.7 0.4

1

 A 90 percent confidence interval (C.I.) is a measure of an estimate’s 

variability. The larger the confidence interval in relation to the size of the 

estimate, the less reliable the estimate.

2

 Federal surveys, including the SIPP 2004 Panel, give respondents 

the option of reporting more than one race. These data can be shown in 

two ways; (1) as mutually exclusive from other race groups, which may be 

denoted by “alone” or (2) not mutually exclusive with other race groups, 

denoted by “alone or in combination with other race groups.” The figures,

tables, and text in this report show race using the first method. The SIPP 

2001 Panel did not allow respondents to report more than one race.

3

 Hispanics may be any race, data in this report for Hispanics overlap 

data for racial groups. Data users should exercise caution when interpreting aggregate results for these groups because they consist of many distinct 

subgroups that differ in socioeconomic characteristics, culture, and recency 

of immigration.

Source: U.S. Census Bureau, Survey of Income and Program 

Participation, 2004 Panel. For information on confidentiality protection

and sampling and nonsampling error, see <http://www.census.gov/sipp

/source.html>.
22 U.S. Census Bureau Table A-9. Annual Poverty by Selected Characteristics: 2001–2003 (Numbers in thousands) Characteristic 2001 1 2002 1 2003 1 Total In poverty using annual income and threshold Total In poverty using annual income and threshold Total In poverty using annual income and threshold Number Percent Number Percent Number Percent Esti- mate 90 per- cent C.I. 2 (+/-) Esti- mate 90 per- cent C.I. 2 (+/-) Esti- mate 90 per- cent C.I. 2 (+/-) Esti- mate 90 per- cent C.I. 2 (+/-) Esti- mate 90 per- cent C.I. 2 (+/-) Esti- mate 90 per- cent C.I. 2 (+/-) All people . . . . . . . . . . . . . . . . . . . . . . . 273,967 29,441 706 10.7 0.3 275,789 29,636 805 10.7 0.3 280,421 30,781 790 11.0 0.3 Race and Hispanic Origin White 3. . . . . . . . . . . . . . . . . . . . . . . . . . . 224,549 19,456 589 8.7 0.3 225,500 19,323 667 8.6 0.3 229,271 20,426 660 8.9 0.3 White, non-Hispanic 4. . . . . . . . . . . . . . 193,274 13,784 502 7.1 0.3 193,202 13,283 561 6.9 0.3 194,637 14,123 557 7.3 0.3 Black 3. . . . . . . . . . . . . . . . . . . . . . . . . . . 34,754 8,141 391 23.4 1.0 35,232 8,414 452 23.9 1.1 35,931 8,457 437 23.5 1.1 Hispanic 4 . . . . . . . . . . . . . . . . . . . . . . . . 34,338 6,307 346 18.4 0.9 35,641 6,658 404 18.7 1.0 37,963 7,037 400 18.5 1.0 Non-Hispanic. . . . . . . . . . . . . . . . . . . . . . 239,629 23,134 636 9.7 0.3 240,148 22,978 721 9.6 0.3 242,457 23,743 706 9.8 0.3 Age Under 18 years. . . . . . . . . . . . . . . . . . . . 71,434 11,400 460 16.0 0.6 71,394 11,620 527 16.3 0.7 71,477 11,583 508 16.2 0.7 18 to 64 years. . . . . . . . . . . . . . . . . . . . . 170,139 15,107 524 8.9 0.3 172,106 15,261 599 8.9 0.3 176,147 16,138 593 9.2 0.3 65 years and over. . . . . . . . . . . . . . . . . . 32,394 2,934 238 9.1 0.7 32,289 2,755 262 8.5 0.8 32,797 3,059 266 9.3 0.8 Family status In married-couple families. . . . . . . . . . . . 179,538 9,323 418 5.2 0.2 180,833 9,494 479 5.2 0.3 183,835 9,974 473 5.4 0.3 In families with a female householder, no husband present . . . . . . . . . . . . . . . 39,445 11,296 458 28.6 1.0 40,516 11,358 522 28.0 1.1 42,232 11,718 511 27.7 1.1 In families with a male householder, no wife present . . . . . . . . . . . . . . . . . . . 11,813 1,128 148 9.5 1.2 10,961 1,111 167 10.1 1.4 11,346 1,240 170 10.9 1.4 Unrelated individuals. . . . . . . . . . . . . . . . 43,171 7,694 381 17.8 0.8 43,479 7,674 432 17.6 0.9 43,008 7,848 422 18.2 0.9 1 Panel and yearly estimates contain different samples. Three-year panel estimates include only respondents in the panel for 9 waves whereas calendar year estimates include people in sample for 12 months. The total number of respondents in each sample are as follows: 47,246 in the 3-year panel; 61,527 in 2001; 57,203 in 2002; and 57,903 in 2003. 2 A 90 percent confidence interval (C.I.) is a measure of an estimate’s variability. The larger the confidence interval in relation to the size of the estimate, the less reliable the estimate. 3 Federal surveys, including the SIPP 2004 Panel, give respondents the option of reporting more than one race. These data can be shown in two ways: (1) as mutually exclusive from other race groups, which may be denoted by “alone” or (2) not mutually exclusive with other race groups, denoted by “alone or in combination with other race groups.” The figures, tables, and text in this report show race using the first method. The SIPP 2001 Panel did not allow respondents to report more than one race. 4 Hispanics may be any race, data in this report for Hispanics overlap data for racial groups. Data users should exercise caution when interpreting aggregate results for these groups because they consist of many distinct subgroups that differ in socioeconomic characteristics, culture, and recency of immigration. Source: U.S. Census Bureau, Survey of Income and Program Participation, 2001 Panel. For information on confidentiality protection and sampling and nonsampling error, see <http://www.census.gov/sipp /source.html>.
U.S. Census Bureau 23 Table A-10. Annual Poverty by Selected Characteristics: 2004–2006 (Numbers in thousands) Characteristic 2004 1 2005 1 2006 1 Total In poverty using annual income and threshold Total In poverty using annual income and threshold Total In poverty using annual income and threshold Number Percent Number Percent Number Percent Esti- mate 90 per- cent C.I. 2 (+/-) Esti- mate 90 per- cent C.I. 2 (+/-) Esti- mate 90 per- cent C.I. 2 (+/-) Esti- mate 90 per- cent C.I. 2 (+/-) Esti- mate 90 per- cent C.I. 2 (+/-) Esti- mate 90 per- cent C.I. 2 (+/-) All people . . . . . . . . . . . . . . . . . . . . . . . 281,963 30,012 573 10.6 0.2 285,073 30,949 630 10.9 0.2 287,299 29,941 905 10.4 0.3 Race and Hispanic Origin White alone 3. . . . . . . . . . . . . . . . . . . . . . 227,517 19,626 474 8.6 0.2 229,484 20,417 524 8.9 0.2 231,210 19,798 753 8.6 0.3 White alone, non-Hispanic 4. . . . . . . . . . 191,669 12,973 391 6.8 0.2 192,263 13,100 426 6.8 0.2 192,755 12,330 603 6.4 0.3 Black alone 3. . . . . . . . . . . . . . . . . . . . . . 35,325 7,981 283 22.6 0.8 35,751 8,084 309 22.6 0.8 35,828 7,560 450 21.1 1.2 Hispanic 4. . . . . . . . . . . . . . . . . . . . . . . . . 38,776 7,269 327 18.7 0.8 40,269 7,841 373 19.5 0.9 41,733 7,997 515 19.2 1.2 Non-Hispanic. . . . . . . . . . . . . . . . . . . . . . 243,187 22,743 507 9.4 0.2 244,804 23,108 554 9.4 0.2 245,566 21,944 789 8.9 0.3 Age Under 18 years. . . . . . . . . . . . . . . . . . . . 71,948 11,646 372 16.2 0.5 72,432 12,011 409 16.6 0.5 72,373 11,575 586 16.0 0.8 18 to 64 years. . . . . . . . . . . . . . . . . . . . . 176,821 16,109 433 9.1 0.2 179,194 16,637 476 9.3 0.3 181,298 15,965 681 8.8 0.4 65 years and over. . . . . . . . . . . . . . . . . . 33,193 2,258 167 6.8 0.5 33,447 2,300 182 6.9 0.5 33,628 2,401 272 7.1 0.8 Family status In married-couple families. . . . . . . . . . . . 182,750 9,324 334 5.1 0.2 184,694 9,886 372 5.4 0.2 186,228 9,560 534 5.1 0.3 In families with a female householder, no husband present . . . . . . . . . . . . . . . 41,933 11,759 373 28.0 0.8 42,804 12,235 412 28.6 0.8 42,781 11,644 587 27.2 1.2 In families with a male householder, no wife present . . . . . . . . . . . . . . . . . . . 12,059 1,432 133 11.9 1.0 11,981 1,398 143 11.7 1.1 11,849 1,182 191 10.0 1.5 Unrelated individuals. . . . . . . . . . . . . . . . 45,221 7,497 301 16.6 0.6 45,594 7,429 325 16.3 0.7 46,442 7,555 477 16.3 1.0 1 Panel and yearly estimates are based on different samples. Three-year panel estimates include only respondents in the panel for 10 waves, whereas calendar year estimates include people in sample for 12 months. The total number of respondents in each sample are as follows: 27,840 in the 3-year panel; 86,128 in 2004; 76,953 in 2005; and 34,372 in 2006. In wave 9 of the SIPP 2004 Panel, a 53 percent sample reduction was made. However, the calendar year weight for 2006 and the 3-year panel weight correct for that sample reduction. 2 A 90 percent confidence interval (C.I.) is a measure of an estimate’s variability. The larger the confidence interval in relation to the size of the estimate, the less reliable the estimate. 3 Federal surveys, including the SIPP 2004 Panel, give respondents the option of reporting more than one race. These data can be shown in two ways: (1) as mutually exclusive from other race groups, which may be denoted by “alone” or (2) not mutually exclusive with other race groups, denoted by “alone or in combination with other race groups.” The figures, tables, and text in this report show race using the first method. 4 Hispanics may be any race, data in this report for Hispanics overlap data for racial groups. Data users should exercise caution when interpreting aggregate results for these groups because they consist of many distinct subgroups that differ in socioeconomic characteristics, culture, and recency of immigration. Source: U.S. Census Bureau, Survey of Income and Program Participation, 2004 Panel. For information on confidentiality protection and sampling and nonsampling error, see <http://www.census.gov/sipp /source.html>.
24 U.S. Census Bureau

Table A-11.

Poverty Entries: People Not in Poverty in 2001 by Poverty Status in 2002 and 2003

(Numbers in thousands)

Characteristic Not in 

poverty in 

2001

In poverty in 2002 In poverty in 2003

Number Percent Number Percent

Estimate

90 percent

C.I. 1 (+/-) Estimate

90 percent 

C.I. 1 (+/-) Estimate

90 percent 

C.I. 1 (+/-) Estimate

90 percent 

C.I. 1 (+/-)

All people . . . . . . . . . . . . . . . . . . . . . . . 236,624 7,451 424 3.1 0.2 10,354 496 4.4 0.2

Race and Hispanic Origin

White 2. . . . . . . . . . . . . . . . . . . . . . . . . . . 198,043 5,520 366 2.8 0.2 7,577 427 3.8 0.2

 White, non-Hispanic 3. . . . . . . . . . . . . . 174,304 3,955 311 2.3 0.2 5,815 376 3.3 0.2

Black 2. . . . . . . . . . . . . . . . . . . . . . . . . . . 25,858 1,512 194 5.8 0.7 2,125 228 8.2 0.9

Hispanic 3. . . . . . . . . . . . . . . . . . . . . . . . . 26,001 1,681 235 6.5 0.9 1,935 251 7.4 1.0

Non-Hispanic. . . . . . . . . . . . . . . . . . . . . . 210,623 5,770 374 2.7 0.2 8,418 449 4.0 0.2

Age

Under 18 years. . . . . . . . . . . . . . . . . . . .

18 to 64 years. . . . . . . . . . . . . . . . . . . . . 59,135 2,624 254 4.4 0.4 3,329 286 5.6 0.5

65 years and over. . . . . . . . . . . . . . . . . . 150,834 4,205 321 2.8 0.2 6,031 382 4.0 0.3

26,655 622 124 2.3 0.5 994 157 3.7 0.6

Family status

In married-couple families. . . . . . . . . . . . 166,760 3,657 299 2.2 0.2 5,283 358 3.2 0.2

In families with a female householder,

 no husband present . . . . . . . . . . . . . . . 26,917 1,905 217 7.1 0.8 2,432 245 9.0 0.9

In families with a male householder,

 no wife present . . . . . . . . . . . . . . . . . . . 9,708 359 95 3.7 1.0 632 125 6.5 1.2

Unrelated individuals. . . . . . . . . . . . . . . . 33,240 1,530 195 4.6 0.6 2,007 223 6.0 0.7

1

 A 90 percent confidence interval (C.I.) is a measure of an estimate’s variability. The larger the confidence interval in relation to the size of the estimate,

the less reliable the estimate. 

2

 Federal surveys, including the SIPP 2004 Panel, give respondents the option of reporting more than one race. These data can be shown in two ways:

(1) as mutually exclusive from other race groups, which may be denoted by “alone” or (2) not mutually exclusive with other race groups, denoted by “alone or

in combination with other race groups.” The figures, tables, and text in this report show race using the first method. The SIPP 2001 Panel did not allow respondents

to report more than one race.

3

 Hispanics may be any race, data in this report for Hispanics overlap data for racial groups. Data users should exercise caution when interpreting aggregate 

results for these groups because they consist of many distinct subgroups that differ in socioeconomic characteristics, culture, and recency of immigration.

Source: U.S. Census Bureau, Survey of Income and Program Participation, 2001 Panel. For information on confidentiality protection and sampling and

nonsampling error, see <http://www.census.gov/sipp/source.html>.
U.S. Census Bureau 25

Table A-12.

Poverty Entries: People Not in Poverty in 2004 by Poverty Status in 2005 and 2006

(Numbers in thousands)

Characteristic Not in 

poverty

in 2004

In poverty in 2005 In poverty in 2006

Number Percent Number Percent

Estimate

90 percent 

C.I. 1 (+/-) Estimate

90 percent 

C.I. 1 (+/-) Estimate

90 percent 

C.I. 1 (+/-) Estimate

90 percent 

C.I. 1 (+/-)

All people . . . . . . . . . . . . . . . . . . . . . . . 242,846 8,416 532 3.5 0.2 10,095 581 4.2 0.2

Race and Hispanic Origin

White Alone 2. . . . . . . . . . . . . . . . . . . . . . 200,505 6,053 453 3.0 0.2 7,312 497 3.6 0.2

 White Alone, non-Hispanic 3. . . . . . . . . 174,013 4,021 371 2.3 0.2 5,115 418 2.9 0.2

Black Alone 2. . . . . . . . . . . . . . . . . . . . . . 26,246 1,771 254 6.7 0.9 2,059 272 7.8 1.0

Hispanic 3. . . . . . . . . . . . . . . . . . . . . . . . . 28,925 2,191 291 7.6 1.0 2,401 304 8.3 1.0

Non-Hispanic. . . . . . . . . . . . . . . . . . . . . . 213,921 6,226 460 2.9 0.2 7,694 509 3.6 0.2

Age

Under 18 years. . . . . . . . . . . . . . . . . . . . 59,459 3,010 322 5.1 0.5 3,331 338 5.6 0.6

18 to 64 years. . . . . . . . . . . . . . . . . . . . . 155,718 4,847 407 3.1 0.3 5,955 450 3.8 0.3

65 years and over. . . . . . . . . . . . . . . . . . 27,669 559 139 2.0 0.5 809 168 2.9 0.6

Family status

In married-couple families. . . . . . . . . . . . 169,673 4,325 385 2.5 0.2 5,373 428 3.2 0.3

In families with a female householder,

 no husband present . . . . . . . . . . . . . . . 28,155 2,130 271 7.6 0.9 2,144 272 7.6 0.9

In families with a male householder,

 no wife present . . . . . . . . . . . . . . . . . . . 9,641 393 117 4.1 1.2 589 143 6.1 1.4

Unrelated individuals. . . . . . . . . . . . . . . . 35,377 1,569 233 4.4 0.6 1,989 262 5.6 0.7

1

 A 90 percent confidence interval (C.I.) is a measure of an estimate’s variability. The larger the confidence interval in relation to the size of the estimate,

the less reliable the estimate. 

2

 Federal surveys, including the SIPP 2004 Panel, give respondents the option of reporting more than one race. These data can be shown in two ways:

(1) as mutually exclusive from other race groups, which may be denoted by “alone” or (2) not mutually exclusive with other race groups, denoted by “alone or

in combination with other race groups.” The figures, tables, and text in this report show race using the first method. The SIPP 2001 Panel did not allow

respondents to report more than one race.

3

 Hispanics may be any race, data in this report for Hispanics overlap data for racial groups. Data users should exercise caution when interpreting aggregate 

results for these groups because they consist of many distinct subgroups that differ in socioeconomic characteristics, culture, and recency of immigration.

Source: U.S. Census Bureau, Survey of Income and Program Participation, 2004 Panel. For information on confidentiality protection and sampling and

nonsampling error, see <http://www.census.gov/sipp/source.html>.
26 U.S. Census Bureau

Table A-13.

Poverty Exits: People in Poverty in 2001 by Poverty Status in 2002 and 2003

(Numbers in thousands)

Characteristic

In poverty 

in 2001

 Not in poverty in 2002 Not in poverty in 2003

Number Percent Number Percent

Estimate

90 percent 

C.I. 1 (+/-) Estimate

90 percent 

C.I. 1 (+/-) Estimate

90 percent 

C.I. 1 (+/-) Estimate

90 percent 

C.I. 1 (+/-)

All people . . . . . . . . . . . . . . . . . . . . . . . 27,930 9,054 465 32.4 1.4 11,325 517 40.5 1.5

Race and Hispanic Origin

White 2. . . . . . . . . . . . . . . . . . . . . . . . . . . 18,356 6,636 400 36.1 1.8 8,268 445 45.0 1.8

 White, non-Hispanic 3. . . . . . . . . . . . . . 12,945 4,938 347 38.1 2.1 6,000 381 46.4 2.2

Black 2. . . . . . . . . . . . . . . . . . . . . . . . . . . 7,804 1,829 212 23.4 2.4 2,324 237 29.8 2.6

Hispanic 3. . . . . . . . . . . . . . . . . . . . . . . . . 5,932 1,916 250 32.3 3.6 2,425 278 40.9 3.8

Non-Hispanic. . . . . . . . . . . . . . . . . . . . . . 21,998 7,138 415 32.4 1.6 8,900 461 40.5 1.7

Age

Under 18 years. . . . . . . . . . . . . . . . . . . . 10,836 3,198 280 29.5 2.2 4,051 315 37.4 2.3

18 to 64 years. . . . . . . . . . . . . . . . . . . . . 14,464 5,085 352 35.2 2.0 6,465 395 44.7 2.1

65 years and over. . . . . . . . . . . . . . . . . . 2,630 771 138 29.3 4.4 810 142 30.8 4.5

Family status

In married-couple families. . . . . . . . . . . . 9,123 3,777 304 41.4 2.6 4,609 335 50.5 2.6

In families with a female householder,

 no husband present . . . . . . . . . . . . . . . 10,798 2,838 264 26.3 2.1 3,714 302 34.4 2.3

In families with a male householder,

 no wife present . . . . . . . . . . . . . . . . . . . 1,018 389 98 38.3 7.6 476 109 46.8 7.8

Unrelated individuals. . . . . . . . . . . . . . . . 6,991 2,049 225 29.3 2.7 2,526 249 36.1 2.9

1

 A 90 percent confidence interval (C.I.) is a measure of an estimate’s variability. The larger the confidence interval in relation to the size of the estimate,

the less reliable the estimate. 

2

 Federal surveys, including the SIPP 2004 Panel, give respondents the option of reporting more than one race. These data can be shown in two ways:

(1) as mutually exclusive from other race groups, which may be denoted by “alone” or (2) not mutually exclusive with other race groups, denoted by “alone or

in combination with other race groups.” The figures, tables, and text in this report show race using the first method. The SIPP 2001 Panel did not allow

respondents to report more than one race.

3

 Hispanics may be any race, data in this report for Hispanics overlap data for racial groups. Data users should exercise caution when interpreting aggregate 

results for these groups because they consist of many distinct subgroups that differ in socioeconomic characteristics, culture, and recency of immigration.

Source: U.S. Census Bureau, Survey of Income and Program Participation, 2001 Panel. For information on confidentiality protection and sampling and

nonsampling error, see <http://www.census.gov/sipp/source.html>.
U.S. Census Bureau 27

Table A-14.

Poverty Exits: People in Poverty in 2004 by Poverty Status in 2005 and 2006 

(Numbers in thousands)

Characteristic

In poverty 

in 2004

Not in poverty in 2005 Not in poverty in 2006

Number Percent Number Percent

Estimate

90 percent 

C.I. 1 (+/-) Estimate

90 percent 

C.I. 1 (+/-) Estimate

90 percent 

C.I. 1 (+/-) Estimate

90 percent 

C.I. 1 (+/-)

All people . . . . . . . . . . . . . . . . . . . . . . . 28,068 8,799 544 31.4 1.6 11,665 622 41.6 1.7

Race and Hispanic Origin

White alone 2. . . . . . . . . . . . . . . . . . . . . . 18,207 6,154 457 33.8 2.1 8,486 534 46.6 2.2

 White alone, non-Hispanic 3. . . . . . . . . . 11,695 4,278 383 36.6 2.6 5,803 444 49.6 2.7

Black alone 2. . . . . . . . . . . . . . . . . . . . . . 7,528 1,885 261 25.0 3.1 2,224 283 29.5 3.2

Hispanic 3. . . . . . . . . . . . . . . . . . . . . . . . . 7,118 2,143 288 30.1 3.5 2,995 337 42.1 3.7

Non-Hispanic. . . . . . . . . . . . . . . . . . . . . . 20,950 6,656 475 31.8 1.9 8,669 540 41.4 2.0

Age

Under 18 years. . . . . . . . . . . . . . . . . . . . 11,120 3,246 334 29.2 2.5 4,186 379 37.6 2.7

18 to 64 years. . . . . . . . . . . . . . . . . . . . . 14,892 5,120 418 34.4 2.3 6,817 480 45.8 2.4

65 years and over. . . . . . . . . . . . . . . . . . 2,055 434 123 21.1 5.3 662 152 32.2 6.1

Family status

In married-couple families. . . . . . . . . . . . 8,903 3,518 348 39.5 3.1 4,477 391 50.3 3.1

In families with a female householder,

 no husband present . . . . . . . . . . . . . . . 10,880 2,566 297 23.6 2.4 3,596 351 33.0 2.7

In families with male householder,

 no wife present . . . . . . . . . . . . . . . . . . . 1,427 711 157 49.8 7.8 726 159 50.8 7.8

Unrelated individuals. . . . . . . . . . . . . . . . 6,858 2,004 263 29.2 3.2 2,866 314 41.8 3.5

1

 A 90 percent confidence interval (C.I.) is a measure of an estimate’s variability. The larger the confidence interval in relation to the size of the estimate,

the less reliable the estimate. 

2

 Federal surveys, including the SIPP 2004 Panel, give respondents the option of reporting more than one race. These data can be shown in two ways:

(1) as mutually exclusive from other race groups, which may be denoted by “alone” or (2) not mutually exclusive with other race groups, denoted by “alone or

in combination with other race groups.” The figures, tables, and text in this report show race using the first method. The SIPP 2001 Panel did not allow

respondents to report more than one race.

3

 Hispanics may be any race, data in this report for Hispanics overlap data for racial groups. Data users should exercise caution when interpreting aggregate 

results for these groups because they consist of many distinct subgroups that differ in socioeconomic characteristics, culture, and recency of immigration.

Source: U.S. Census Bureau, Survey of Income and Program Participation, 2004 Panel. For information on confidentiality protection and sampling and

nonsampling error, see <http://www.census.gov/sipp/source.html>.
28 U.S. Census Bureau

Table A-15.

Poverty Entries and Exits: 2004 Income-to-Poverty Ratio by 2005 Income-to-Poverty Ratio

(Numbers in thousands)

2004

income-to-poverty ratio

2005 income-to-poverty ratio

Total

Less than

100 percent

of the poverty

threshold

100 percent or more of the poverty threshold

Number

90 percent 

C.I. 1 (+/-)

100 to 150 percent

of the poverty

threshold

More than

150 percent of the 

poverty threshold

Number

90 percent 

C.I. 1 (+/-) Number

90 percent 

C.I. 1 (+/-) Number

90 percent 

C.I. 1 (+/-)

Total . . . . . . . . . . . . . . . . . . . . . . . . . . . 270,914 27,864 927 243,229 916 25,196 887 218,033 901

Less than 100 percent of the

 poverty threshold. . . . . . . . . . . . . . . . . . 28,068 19,268 786 8,798 544 5,235 422 3,563 350

100 percent or more of the

 poverty threshold. . . . . . . . . . . . . . . . . . 242,847 8,416 532 234,430 569 19,960 799 214,470 953

100 to 150 percent of the

 poverty threshold. . . . . . . . . . . . . . . . . . 25,740 4,754 403 20,986 817 12,205 636 8,781 543

More than 150 percent of the

 poverty threshold . . . . . . . . . . . . . . . . . 217,107 3,662 354 213,444 967 7,755 511 205,689 1,062

1

 A 90 percent confidence interval (C.I.) is a measure of an estimate’s variability. The larger the confidence interval in relation to the size of the estimate,

the less reliable the estimate.

Source: U.S. Census Bureau, Survey of Income and Program Participation, 2004 Panel. For information on confidentiality protection and sampling and

nonsampling error, see <http://www.census.gov/sipp/source.html>.

Table A-16.

Poverty Entries and Exits: 2004 Income-to-Poverty Ratio by 2006 Income-to-Poverty Ratio

(Numbers in thousands)

2004

income-to-poverty ratio

2006 income-to-poverty ratio

Total

Less than

100 percent

of the poverty

threshold

100 percent or more of the poverty threshold

Number

90 percent 

C.I. 1 (+/-)

100 to 150 percent

of the poverty

threshold

More than

150 percent of the 

poverty threshold

Number

90 percent 

C.I. 1 (+/-) Number

90 percent 

C.I. 1 (+/-) Number

90 percent 

C.I. 1 (+/-)

Total . . . . . . . . . . . . . . . . . . . . . . . . . . . 270,914 26,498 907 244,416 893 24,548 877 219,868 872

Less than 100 percent of the

 poverty threshold. . . . . . . . . . . . . . . . . . 28,068 16,403 730 11,665 622 6,270 461 5,395 429

100 percent or more of the

 poverty threshold. . . . . . . . . . . . . . . . . . 242,847 10,095 581 232,751 614 18,278 767 214,473 952

100 to 150 percent of the

 poverty threshold. . . . . . . . . . . . . . . . . . 25,740 4,856 407 20,884 816 9,713 570 11,171 609

More than 150 percent of the

 poverty threshold . . . . . . . . . . . . . . . . . 217,107 5,239 423 211,867 987 8,565 537 203,302 1,088

1

 A 90 percent confidence interval (C.I.) is a measure of an estimate’s variability. The larger the confidence interval in relation to the size of the estimate,

the less reliable the estimate.

Source: U.S. Census Bureau, Survey of Income and Program Participation, 2004 Panel. For information on confidentiality protection and sampling and

nonsampling error, see <http://www.census.gov/sipp/source.html>.
U.S. Census Bureau 29

Table A-17.

People in Poverty Across the 3-year and 4-year Periods of the SIPP 2004 Panel

(Numbers in thousands)

Period

Total

People in poverty for period

Number Percent

Estimate

90 percent

C.I. 2 (+/-) Estimate

90 percent

C.I. 2 (+/-)

3-year panel (2004–2006)

Poor at least 2 months. . . . . . . . . . . 270,914 78,348 1,361 28.9 0.5

Poor every month. . . . . . . . . . . . . . 270,914 7,554 505 2.8 0.2

4-year panel (2004–2007) 1, 3

Poor at least 2 months. . . . . . . . . . . 267,212 84,460 1,686 31.6 0.6

Poor every month. . . . . . . . . . . . . . 266,819 5,832 469 2.2 0.2

2004 1

Poor at least 2 months. . . . . . . . . . . 281,963 59,203 749 21.0 0.3

Annual poverty rate. . . . . . . . . . . . . 281,963 30,012 573 10.6 0.2

2005 1

Poor at least 2 months. . . . . . . . . . . 285,073 57,780 807 20.3 0.3

Annual poverty rate. . . . . . . . . . . . . 285,073 30,949 630 10.9 0.2

2006 1

Poor at least 2 months. . . . . . . . . . . 287,299 55,824 1,162 19.4 0.4

Annual poverty rate. . . . . . . . . . . . . 287,299 29,941 905 10.4 0.3

2007 1, 4

Poor at least 2 months. . . . . . . . . . . 291,617 57,191 4,921 19.6 1.5

Annual poverty rate. . . . . . . . . . . . . 291,617 32,034 3,701 11.0 1.2

1

 Panel and yearly estimates are based on different samples. The 3- and 4-year panel estimates include only respondents in the panel for 10 and 12 waves, 

respectively, whereas annual estimates include people in the sample for the calendar year. The total number of respondents in each sample are as follows:

27,840 in the 3-year panel; 25,916 in the 4-year panel; 86,128 in 2004; 76,953 in 2005; 34,372 in 2006; and 34,489 in 2007. In wave 9 of the SIPP 2004 Panel,

a 53 percent sample reduction was made. However, the calendar year weights for 2006 and 2007 and the 3- and 4-year panel weights correct for this. The 4-year 

and 2007 estimates use the carry forward imputation method to account for months October, November, December 2007 being missing for some of the rotation 

groups. When the carry forward imputation method was unreliable, rotations groups were excluded. See notes 3 and 4 for more details.

2

 A 90 percent confidence interval (C.I.) is a measure of an estimate’s variability. The larger the confidence interval in relation to the size of the estimate,

the less reliable the estimate.

3

 The 4-year panel estimates of being in poverty for at least 2 months exclude rotation group 3 and estimates are weighted up by 4/3 to represent the underlying 

SIPP population. The respective “a” and “b” parameters used to create the standard errors were also inflated by a factor of 4/3.

4

 When estimating the percent of the 2007 population in poverty for at least 2 months and in poverty for the year, rotation group 1 was excluded and estimates 

were weighted up by 4/3. The respective “a” and “b” parameters used to create the standard errors were also inflated by a factor of 4/3.

Source: U.S. Census Bureau, Survey of Income and Program Participation, 2004 Panel. For information on confidentiality protection and sampling and

nonsampling error, see <http://www.census.gov/sipp/source.html>.
30 U.S. Census Bureau

Table A-18.

The Duration of Poverty Spells Across the 3- and 4-year Periods of the 2004 Panel

(Excludes spells underway in January 2004)

Spell characteristic Estimate 90 percent C.I. 1 (+/-)

Percent of spells in interval

2004–2006 2

2 to 4 months. . . . . . . . . . . . . . . . . . . . . . . 47.7 1.3

5 to 8 months. . . . . . . . . . . . . . . . . . . . . . . 19.9 1.1

9 to 12 months. . . . . . . . . . . . . . . . . . . . . . 9.2 0.8

13 to 16 months. . . . . . . . . . . . . . . . . . . . . 5.3 0.6

17 to 20 months. . . . . . . . . . . . . . . . . . . . . 2.9 0.4

21 to 24 months. . . . . . . . . . . . . . . . . . . . . 2.6 0.4

25 or more months. . . . . . . . . . . . . . . . . . 12.4 0.9

2004–2007 2

2 to 4 months. . . . . . . . . . . . . . . . . . . . . . . 46.0 1.3

5 to 8 months. . . . . . . . . . . . . . . . . . . . . . . 19.8 1.1

9 to 12 months. . . . . . . . . . . . . . . . . . . . . . 9.1 0.8

13 to 16 months. . . . . . . . . . . . . . . . . . . . . 4.9 0.6

17 to 20 months. . . . . . . . . . . . . . . . . . . . . 2.9 0.5

21 to 24 months. . . . . . . . . . . . . . . . . . . . . 2.6 0.4

25 to 36. . . . . . . . . . . . . . . . . . . . . . . . . . . 4.0 0.5

37 or more months 3. . . . . . . . . . . . . . . . . 6.7 1.3

Median spell length

(in months)

2004–2006 2. . . . . . . . . . . . . . . . . . . . . . . 4.5 0.2

2004–2007 2. . . . . . . . . . . . . . . . . . . . . . . 4.9 0.2

1

 A 90 percent confidence interval (C.I.) is a measure of an estimate’s variability. The larger the confidence interval in relation to the size of the estimate,

the less reliable the estimate.

2

 The 3-year and 4-year are based on different samples. The 3- and 4-year panel estimates include respondents in the panel for 10 and 12 waves,

respectively, and the total number of respondents in each sample are: 27,840 in the 3-year panel and 25,916 in the 4-year panel. In wave 9 of the SIPP 2004 Panel, 

a 53 percent sample reduction was made. However, the calendar year weights for 2006 and 2007 and the 3- and 4-year panel weights correct for that sample 

reduction. The 4-year estimates use the carry forward imputation method to account for months October, November, December 2007 being missing for some of the 

rotation groups. When the carry forward imputation method was unreliable, rotations groups were excluded. See note 3 for more details.

3

 The 4-year panel estimate of the percentage of people in poverty 37 or more months excludes rotation groups 1, 2, and 3, and the estimate was weighted 

up by a factor of 4 to represent the underlying SIPP population. The respective “a” and “b” parameters used to create the standard errors were also inflated by a 

factor of 4. As such, the base used to calculate to percentage of spells lasting 37 or more months (approximately 113 million spells) differs from the base used to 

calculate the other intervals (approximately 105 million spells) and the total percentage of spells does not add up to 100 percent.

Source: U.S. Census Bureau, Survey of Income and Program Participation, 2004 Panel. For information on confidentiality protection and sampling and

nonsampling error, see <http://www.census.gov/sipp/source.html>.

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