An Overview of the
American Community Survey
1
1
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 a
sample, 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 Survey
Content
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
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
11
11
American Community Survey
Target 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
12
12
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
13
13
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
14
14
American Community Survey
Data Products Release Schedule
Data Product
Population Size
of Area
2006
1-Year Estimates
for Data Collected in:
65,000+
3-Year Estimates
for Data Collected in:
20,000+
5-Year Estimates
for Data Collected in:
All Areas*
2005
2007
2008
Data released in:
2009
2010
2011
2012
2013
2006
2007
2008
2010
2011
2012
2009
2005-2007 2006-2008 2007-2009 2008-2010 2009-2011 2010-2012
2005-2009 2006-2010 2007-2011 2008-2012
* Five-year estimates will be available for areas as small as census tracts and block groups.
Source: US Census Bureau
15
15
American Community Survey
Data 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
16
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
17
17
American Community Survey
ACS Main Page
http://www.census.gov/acs/www
18
18
American Community Survey
2007 Data Release
http://www.census.gov/acs/www/Products/
19
19
American Community Survey
2007 Data Product Details
http://www.census.gov/acs/www/Products/users_guide/
20
20
American Community Survey
2007 Data Product Details
21
21
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.
22
22
American Community Survey
Comparing Data
http://www.census.gov/acs/www/UseData/compACS.htm
23
23
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
24
American Community Survey
Similarities 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
25
25
American Community Survey
Key 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
26
26
American Community Survey
Key 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
27
27
Geographic Areas and Concepts for
the American Community Survey
28
28
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
29
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
30
Census Geographic Concepts
Legal/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
31
ACS Geographic Area Types
U.S. and Puerto Rico
Type of Geographic Area
States, District of Columbia,
and Puerto Rico
Congressional Districts
Public Use Microdata Areas
Metropolitan and Micropolitan
Statistical Areas
Urban Areas
32
Total
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
52
100.0
100.0
435
100.0
100.0
2,071
99.9
100.0
952
53.6
96.8
3,646
10.8
23.4
Hierarchy of Census Geographic Entities
33
33
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
Public Use Microdata Areas
35
ACS Geographic Area Types
U.S. and Puerto Rico
Number of Areas
with a Population
of 65,000 or more
Number of Areas
with a Population
of 20,000 or more
3,219
800
1,882
County Subdivision
21,171
187
999
Place
25,292
520
2,081
952
510
922
3,646
394
854
Type of Geographic Area
County
Metropolitan and Micropolitan
Statistical Areas
Urban Areas
36
Total
Number
of Areas
Understanding Multiyear Estimates from
the American Community Survey
37
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
38
What are multiyear estimates?
39
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
40
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
41
Population Thresholds for ACS Estimates
65,000 +
people
20,000+
people
Less than
20,000
people
42
1-year
estimates
3-year
estimates
5-year
estimates
X
X
X
X
X
X
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.”
43
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
44
When should I use multiyear
estimates?
45
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
46
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
47
Reliability
Note: Fictional data
48
What should I be aware of when
using multiyear estimates?
49
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
50
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
51
Geographic Boundaries
Amarillo city, Texas
52
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
53
How can I use multiyear
estimates
to make comparisons?
54
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
55
Counties in Kentucky, by Population Size
Figure 3: Counties in Kentucky by Population Size, 2007
Population, July 2007
Population, July 2007
Less than 20,000 people
20,000 to 64,999 people
65,000 or more people
0.00 to 20000.00
20000.00 to 65000.00
65000.00 to 800000.00
Source: U.S. Census Bureau, American Community Survey Handbook for General Audiences.
56
Comparing Data in 2010
Fayette County
Franklin County
Fulton County
57
2009
2007-2009
2005-2009
X
X
X
X
X
X
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
58
Overlapping Periods
59
Introduction to the
Public Use Microdata Sample
(PUMS)
File from the American
Community Survey
60
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?
61
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
62
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
63
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
64
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?
65
Geographic Areas in the ACS PUMS
• Nation
• All states, D.C., Puerto Rico
• Public Use Microdata Areas (PUMAs)
66
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
67
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
68
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
69
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
70
Housing Topics Covered in ACS PUMS
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
71
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
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
72
Downloading ACS PUMS data
American FactFinder
73
Downloading ACS PUMS data
American FactFinder
74
http://factfinder.census.gov/home/en/acs_pums_2007_3yr.ht
ml
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
75
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
76
DataFerrett Website
http://dataferrett.census.gov/
77
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
78
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