1

1

An Overview of the American Community Survey

Overview

• What is the American Community Survey?

• Content

• Survey Methodology

• Data Products

• How is it different from Census 2000?

2

What is the American Community Survey?

3

3

Decennial Census

•In Census 2000, the census used 2 forms

1.“short” form – asked for basic demographic and housing information, such as age, sex, race, how many people lived in the housing unit, and if the housing unit was owned or rented by the resident

2.“long” form – collected the same information as the short form but also collected more in-depth information such as income, education, and language spoken at home

•Only a small portion of the population, called asample, received the long form.

4

4

2010 Census and American Community Survey

• 2010 Census will focus on counting the U.S. population

• The sample data are now collected in the ACS

• Puerto Rico is the only U.S. territory where the ACS is conducted

• 2010 Census will have a long form for U.S. territories such as Guam and U.S. Virgin Islands

• Same “short form” questions on the ACS

5

5

American Community SurveyContent

6

6

American Community Survey Social Characteristics

• •Education• Marital Status• Fertility• Grandparent Caregivers• Veterans• Disability Status

7

7

American Community Survey Economic Characteristics

• Income• Benefits• Employment Status• Occupation• Industry• Commuting to Work• Place of Work

8

8

American Community Survey Housing Characteristics

• Tenure• Occupancy & Structure• Housing Value• Taxes & Insurance• Utilities• Mortgage/Monthly Rent

9

9

American Community Survey Demographic Characteristics

• Sex• Age• Race• Hispanic Origin

10

10

11

11

American Community Survey Methodology

• Sample includes about 3 million addresses each year

• Three modes of data collection– mail– phone– personal visit

• Data are collected continuously throughout the year

12

12

American Community SurveyTarget Population

• Resident population of the United States and Puerto Rico

– Living in housing units and group quarters

• Current residents at the selected address

– “Two month” rule

13

13

American Community Survey

Group Quarters

• Place where people live or stay that is normally owned or managed by an entity or organization providing housing or services for the residents.

• 2 categories of group quarters:

– Institutional– Non-institutional

14

14

American Community Survey Period Estimates

• ACS estimates are period estimates, describing the average characteristics over a specified period

• Contrast with point-in-time estimates that describe the characteristics of an area on a specific date

• 1-year, 3-year, and 5-year estimates will be released for geographic areas that meet specific population thresholds

American Community Survey Data Products Release Schedule

15

15

Data Product Population Size Data released in: of Area 2006 2007 2008 2009 2010 2011 2012 2013

1-Year Estimates 65,000+ 2005 2006 2007 2008 2009 2010 2011 2012for Data Collected in:

3-Year Estimates 20,000+ 2005-2007 2006-2008 2007-2009 2008-2010 2009-2011 2010-2012for Data Collected in:

5-Year Estimates All Areas* 2005-2009 2006-2010 2007-2011 2008-2012for Data Collected in:

* Five-year estimates will be available for areas as small as census tracts and block groups.Source: US Census Bureau

16

American Community SurveyData Products

• Profiles– Data Profiles– Narrative Profiles– Comparison Profiles– Selected Population Profiles

• Tables– Detailed Tables– Subject Tables– Ranking Tables– Geographic Comparison Tables

• Thematic Maps• Public Use Microdata Sample (PUMS) Files

17

17

American Community Survey Learning More

• ACS Main Page

• 2007 Data Product Details

• Subject Definitions

• Guidance on Comparing 2007 Data to Other Sources

• Design and Methodology Report

• The ACS Compass Products

American Community SurveyACS Main Page

18

18http://www.census.gov/acs/www

American Community Survey 2007 Data Release

19

19http://www.census.gov/acs/www/Products/

American Community Survey 2007 Data Product Details

20

20http://www.census.gov/acs/www/Products/users_guide/

American Community Survey 2007 Data Product Details

21

21

22

22

American Community Survey Comparison Guidance

• Comparing 2008 ACS to 2007 ACS– Census Bureau supports comparisons made between

2007 and 2008 ACS data

• Comparing 2008 ACS to Census 2000– Differences between the 2008 ACS and Census 2000

include residence rules, universes, and reference periods.

American Community Survey Comparing Data

23

23http://www.census.gov/acs/www/UseData/compACS.htm

24

American Community Survey The ACS Compass Products

• Set of educational handbooks aimed at specific audiences

• Presentation slides on important ACS topics

• E-learning tutorial

24

25

25

American Community SurveySimilarities with Census 2000

• Same questions and many of the same basic statistics

• 5-year estimates will be produced for same broad set of geographic areas including census tracts and block groups

26

26

American Community SurveyKey Differences from Census 2000

• Beginning in 2010, data for small geographic areas will be produced every year versus once every 10 years

• Data for larger areas are available now and data for mid sized area will be available in December 2008

• Census 2000 data described the population and housing as of April 1, 2000 while ACS data describe a period of time and require data for 12 months, 36 months, or 60 months

27

27

American Community SurveyKey Differences from Census 2000

• The goal of ACS is to produce data comparable to the Census 2000 long form data

• These estimates will cover the same small areas as Census 2000 but with smaller sample sizes

• Smaller sample sizes for 5-year ACS estimates results in reductions in the reliability of estimates

28

28

Geographic Areas and Concepts for the American Community Survey

29

Overview of Session

• Basic Census Bureau geography

• Geographic areas for which ACS data are available– 2007 1-year estimates– 2005-2007 3-year estimates

• Geographic area concept and definition issues to be aware of when using ACS data

30

What is not covered?

• Small geographic areas that will only appear in 5-year products– Block groups and census tracts

• Geography products, such as maps, shapefiles, and relationship files

• Geographic entity codes, such as FIPS codes

31

Census Geographic ConceptsLegal/Administrative and Statistical Areas

Legal/Administrative Areas Statistical Areas

Nation Regions

States Divisions

Counties Census County Divisions

Minor Civil Divisions Census Designated Places

Incorporated Places Metropolitan and Micropolitan Statistical Areas

Congressional Districts Urban / Rural Areas

School Districts Census Tracts

Voting Districts Block Groups

ZIP Code Tabulation Areas Public Use Microdata Areas

32

ACS Geographic Area Types U.S. and Puerto Rico

Type of Geographic AreaTotal

Number of Areas

Percent of Areas with a Population of 65,000 or more

Percent of Areas with a Population of 20,000 or more

States, District of Columbia, and Puerto Rico 52 100.0 100.0

Congressional Districts 435 100.0 100.0

Public Use Microdata Areas 2,071 99.9 100.0

Metropolitan and Micropolitan Statistical Areas 952 53.6 96.8

Urban Areas 3,646 10.8 23.4

33

33

Hierarchy of Census Geographic Entities

Public Use Microdata Areas (PUMAs)

• Minimum population of 100,000• Cannot cross state boundaries• Composed of:

– Census tracts– Places – One or more Counties – Combination of Tracts and Counties

34

34

35

Public Use Microdata Areas

36

ACS Geographic Area Types U.S. and Puerto Rico

Type of Geographic AreaTotal

Number of Areas

Number of Areas with a Population of 65,000 or more

Number of Areas with a Population of 20,000 or more

County 3,219 800 1,882

County Subdivision 21,171 187 999

Place 25,292 520 2,081

Metropolitan and Micropolitan Statistical Areas 952 510 922

Urban Areas 3,646 394 854

37

Understanding Multiyear Estimates from the American Community Survey

38

Overview

• What are multiyear estimates?

• When should you use multiyear estimates?

• What should you be aware of when using multiyear estimates?

• How can you use multiyear estimates to make comparisons?

• Example of using multiyear estimates

39

What are multiyear estimates?

40

What is a Period Estimate?

Definition

An estimate that describes the average characteristics of an area over a specific time period

Period for ACS 1-year estimates is the calendar year

Different from a point-in-time estimate

41

What is a Multiyear Estimate?

Definition

A period estimate that encompasses more than one calendar year

Period for ACS multiyear estimates is either 3 or 5 calendar years

42

Population Thresholds for ACS Estimates

1-year estimates

3-year estimates

5-year estimates

65,000 + people X X X

20,000+ people X X

Less than 20,000 people

X

43

How to Label Multiyear Estimates

• ACS estimates based on data collected from 2005-2007 should not be labeled “2006” or “2007” estimates

• Multiyear estimates do not represent any one year or the midpoint of a period

• Correct labeling for multiyear estimate: “The child poverty rate for the 2005-2007 period was X percent.”

44

Constructing Multiyear Estimates

• Data are pooled across 36 or 60 months

• Data are weighted to produce estimates

• Estimates are controlled for age, sex, race, and Hispanic origin

• Multiyear estimates are not an average of 1-year estimates

45

When should I use multiyear estimates?

46

Use Multiyear Estimates When …

• No 1-year estimate is available

• Margins of error for 1-year estimates are larger than required

• Analyzing data for small population groups

47

Currency vs. Reliability

Currency Reliability

1-year estimates provide information based on the last year

Larger sample sizes produce estimates that are more statistically reliable

3-year estimates provide information based on the last year and the 2 years before that

3-year estimates are based on 3 times as many sample cases as 1-year estimates

5-year estimates provide information based on the last year and the 4 years before that

5-year estimates are based on 5 times as many sample cases as 1-year estimates

48

Reliability

Note: Fictional data

49

What should I be aware of when using multiyear estimates?

50

Inflation Adjustment

• Dollar-valued data items are inflation adjusted to the most recent year for the period

• Income, rent, home value, and energy costs

• Adjusted using inflation factors based on the Consumer Price Index (CPI)

• Adjustment designed to put the data into dollars with equal purchasing power

51

Geographic Boundaries

• Multiyear estimates are based on geographic boundaries as of January 1 of the last year in the multiyear period

• Boundary Annexation Survey collects boundary changes

• Boundaries of other statistical areas will be updated every decade in conjunction with the decennial census

52

Geographic Boundaries Amarillo city, Texas

53

Population Controls

• Estimates of housing units and people are controlled to the population estimates derived from the Population Estimates Program

• Multiyear estimates are controlled to the average of the individual year’s estimates for the period

54

How can I use multiyear estimates to make comparisons?

55

Comparing Across Geographies

• Only compare the same type of estimate

• 1-year estimates to other 1-year estimates

• 3-year estimates to other 3-year estimates

• 5-year estimates to other 5-year estimates

• Same time period

56

Counties in Kentucky, by Population Size

Source: U.S. Census Bureau, American Community Survey Handbook for General Audiences.

Less than 20,000 people20,000 to 64,999 people65,000 or m ore people

Population, July 2007

Figure 3: Counties in Kentucky by Population Size, 2007

P opulation, July 2007

0.00 to 20000.00

20000.00 to 65000.00

65000.00 to 800000.00

57

Comparing Data in 2010

2009 2007-2009 2005-2009

Fayette County X X X

Franklin County X X

Fulton County X

58

Comparing Across Time Periods

• Same geographic area– Use caution if geographic boundaries

have changed over time– Easier to compare non-overlapping

periods– Make comparisons using the same

length time period

59

Overlapping Periods

60

Introduction to the Public Use Microdata Sample (PUMS)

File from the American Community Survey

61

Overview

• What is the ACS Public Use Microdata Sample (PUMS) file?

• What geographic areas are available in the ACS PUMS?

• How does the Census Bureau protect confidentiality in the ACS PUMS?

• How do I access ACS PUMS data?

62

What is the ACS PUMS file?

• A sample of population and housing unit records from the American Community Survey

• Allows users to create custom tables that are not available through pretabulated ACS products

• The 1-year ACS PUMS file represents 1 percent of the U.S. population

63

Summary Data and Microdata What’s the Difference?

• Summary data are predefined tables for specific geographic areas (states, counties, etc.)

• In the ACS microdata, the basic unit is an individual housing unit or person

64

Who Should Use the ACS PUMS?

• People who want to create tables that are not available through American FactFinder

• People who need data for small or unique population groups

• People interested in mapping population and housing characteristics

65

Sample Questions That the ACS PUMS Could Answer

• What proportion of children ages 5 to 9 live in households that do not have telephone service?

• What is the veteran status of college students living in Maine?

• What proportion of low-income workers in Kentucky commute 90+ minutes to work?

66

Geographic Areas in the ACS PUMS

• Nation

• All states, D.C., Puerto Rico

• Public Use Microdata Areas (PUMAs)

67

What are PUMAs?

• Predefined areas with 100,000+ residents

• Combinations of adjacent counties and census tracts within states

• PUMA boundaries match those used in Census 2000, with exception of Louisiana

68

Identifying PUMAs

• PUMAs are identified by a five-digit number, unique within each state

• Geographic equivalency files show how other areas align with PUMA boundaries– Located on the PUMS download page on

American FactFinder: http://factfinder.census.gov/home/en/acs_pums_2007_3yr.html

• Census 2000 PUMAs will continue to be used until after the 2010 Census

69

Protecting Confidentiality in the ACS PUMS

• Title 13 requires the Census Bureau to keep all personal information strictly confidential:

– By stripping personal information from records

– Through “data swapping,” “top coding,” and “bottom coding”

– By including only a sample of ACS responses

– By limiting geographic areas on the PUMS

70

Accessing PUMS Files

• Data can be downloaded through FactFinder and analyzed with statistical software

• Or accessed through the menu-driven DataFerrett system

• Refer to PUMS data dictionary http://factfinder.census.gov/home/en/acs_pums_2007_1yr.html

71

Housing Topics Covered in ACS PUMS

• Bedrooms • Condominium status • Contract rent (monthly rent) • Cost of utilities and fuels • Family income • Family and household

relationships • Farm status and value • Fire, hazard, and flood

insurance • Food Stamps • Fuels used • Gross rent • House heating fuel • Household income • Household type • Kitchen facilities • Linguistic isolation

• Meals included in rent • Mortgage status and owner

costs • Plumbing facilities • Presence and age of own

children • Presence of subfamilies in

household • Property value • Real estate taxes • Residence state • Rooms • Telephone in housing unit • Tenure • Units in structure • Vacancy status • Vehicles available • Year householder moved into

unit • Year structure built

72

Person Topics Covered in ACS PUMS

• Ability to speak English • Age • Ancestry • Citizenship • Class of worker • Disability status • Educational attainment • Fertility • Hispanic origin • Hours worked • Income by type • Industry • Language spoken at home • Last week work status • Marital status • Means of transportation to work • Migration

• Military status and periods of service

• Mobility status • Occupation • Personal care limitation • Place of birth • Place of work • Poverty status • Race • Relationship • School enrollment and type of

school • Sex • Time of departure for work • Travel time to work • Vehicle occupancy • Weeks worked • Work status • Work limitation status • Year of entry

73

Downloading ACS PUMS data American FactFinder

74

Downloading ACS PUMS data American FactFinder

http://factfinder.census.gov/home/en/acs_pums_2007_3yr.html

75

Other PUMS Resources American FactFinder

• Values used in top- and bottom-coding the variables

• Detailed codes for ancestry, occupation, etc.

• Links to geographic equivalency files

• Accuracy of the PUMS and methods of calculating sampling error

76

Analyzing PUMS Data DataFerrett

• Can be used to extract PUMS data using a menu-driven system

• Need to register to use DataFerrett

• Download DataFerrett and install it on your computer

77

DataFerrett Website

http://dataferrett.census.gov/

78

Availability of ACS PUMS Data

• Available each year beginning in 2000

• 2007 ACS 1-year PUMS released September 2008

• 2005-2007 ACS 3-year PUMS released January 2009

Other Sources for ACS Data

• Microdata– Integrated Public Use Microdata Series

(IPUMS) from Minnesota Population Center: www.ipums.org

– PDQ-Explore: www.pdq.com

• Aggregate Data– Social Explorer: www.socialexplorer.com – Brookings State of Metropolitan

America: www.brookings.edu/metro/StateOfMetroAmerica/Map.aspx