The American Community Survey: The Census Bureau’s new annual survey of America Will “Chip” Sawyer Vermont State Data Center.

The American Community The American Community Survey:Survey:The Census Bureau’s new annual survey The Census Bureau’s new annual survey of Americaof America

Will “Chip” Sawyer

Vermont State Data Center

Background on the ACSBackground on the ACS

• An ongoing year-round sample survey An ongoing year-round sample survey of ~3 mil. householdsof ~3 mil. households– and a sample of group quartersand a sample of group quarters

• In Development since late 1990’sIn Development since late 1990’s• Provides annual data releasesProvides annual data releases

– Nationwide since 2005Nationwide since 2005• Meant to “replace” the decennial “long Meant to “replace” the decennial “long

form.”form.”– income, disability, employment, education, income, disability, employment, education,

ancestry, cost and condition of housing, ancestry, cost and condition of housing, etc.etc.

Background on the ACSBackground on the ACS

• Display Display Characteristics of the Characteristics of the PopulationPopulation– Not Head CountsNot Head Counts

• ACS data are controlled to county ACS data are controlled to county level Census Population Estimateslevel Census Population Estimates

4

Key Differences from Key Differences from Decennial “Long Form”Decennial “Long Form”• Data are Period Estimates, not point-in-timeData are Period Estimates, not point-in-time

– 12 months, 36 months, or 60 months.12 months, 36 months, or 60 months.

– or 1-year, 3-year and 5-year.or 1-year, 3-year and 5-year.

• Margins of Error accompany the dataMargins of Error accompany the data

– ACS data are actually rangesACS data are actually ranges

• ACS Residence Rule is different from decennial CensusACS Residence Rule is different from decennial Census

– ““More than 2 months” vs. “most of the time”More than 2 months” vs. “most of the time”

• Some tables suppressed or collapsedSome tables suppressed or collapsed

– Reasons: reliability and confidentialityReasons: reliability and confidentiality

Changes: The American Community Survey

What is a Period Estimate?What is a Period Estimate?

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

• The period for ACS 1-year estimates is the 12 months that The period for ACS 1-year estimates is the 12 months that make up the calendar year.make up the calendar year.

• A 5-year ACS estimate means that all the data collected for A 5-year ACS estimate means that all the data collected for 60 months (e.g., January 2005 through December 2009) are 60 months (e.g., January 2005 through December 2009) are averaged to come up with one estimate.averaged to come up with one estimate.

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

• Inflation is controlled to the final year of the estimate.Inflation is controlled to the final year of the estimate.

Period Estimates and Sample SizePeriod Estimates and Sample Size

Combine Combine years to years to build up build up the the sample sample sizesize

From “From “2008 ACS Accuracy of the Data (US)”2008 ACS Accuracy of the Data (US)”at http://www.census.gov/acs/www/UseData/Accuracy/Accuracy1.htmat http://www.census.gov/acs/www/UseData/Accuracy/Accuracy1.htm

7

ACS Release ScheduleACS Release Schedule

Nebraska ACS Data Nebraska ACS Data

• Thanks to Jerry Deichert for dataThanks to Jerry Deichert for data

• Omaha city was an ACS test site: Omaha city was an ACS test site: 1997-20041997-2004– Can examine 1, 3, 5-year dataCan examine 1, 3, 5-year data

ACS: Multi-Year ACS: Multi-Year EstimatesEstimates

Example of 5-year average graph

40

50

60

70

80

90

100

2005-2009 2006-2010 2007-2011 2008-2012 2009-2013 2010-2014

5-year period

Ave

rag

e %

Only two values truly independent of each other

– Were always there...Were always there...

• But ACS puts them front and centerBut ACS puts them front and center– Need to be displayed and used from Need to be displayed and used from

now onnow on– Help you to keep from interpreting small Help you to keep from interpreting small

or nonexistent differences as importantor nonexistent differences as important• i.e. two figures within each others’ margins i.e. two figures within each others’ margins

of error probably aren’t statistically differentof error probably aren’t statistically different– whether you’re comparing in time or spacewhether you’re comparing in time or space

– Set at a 90% Confidence IntervalSet at a 90% Confidence Interval

ACS: Margins of ErrorACS: Margins of Error

ACS: Margins of ErrorACS: Margins of Error

• So...So...– Actual 2008 VT median age is 41.2 to 41.8Actual 2008 VT median age is 41.2 to 41.8

• that’s the confidence intervalthat’s the confidence interval

People Moving to North Dakota Within the People Moving to North Dakota Within the Past Year by State of Origin: 2006 ACSPast Year by State of Origin: 2006 ACS

-500

0

500

1000

1500

2000

2500

Mon

tana

Sou

th D

akot

a

Cal

iforn

ia

Col

orad

o

Ariz

ona

Mic

higa

n

Tex

as

Okl

ahom

a

Pen

nsyl

vani

a

Was

hing

ton

Ten

ness

ee

Mis

siss

ippi

Flo

rida

New

Yor

k

Neb

rask

a

Virg

inia

Idah

o

Wis

cons

in

Mis

sour

i

Wyo

min

g

Ore

gon

Ohi

o

Geo

rgia

Iow

a

Illin

ois

New

Mex

ico

Ken

tuck

y

Ala

ska

Nev

ada

Haw

aii

Loui

sian

a

Ala

bam

a

Mas

sach

uset

ts

Mar

ylan

d

Con

nect

icut

Sou

th C

arol

ina

Ark

ansa

s

Nor

th C

arol

ina

Kan

sas

Del

awar

e

Dis

tric

t of

Col

umbi

a

Indi

ana

Mai

ne

New

Ham

pshi

re

New

Jer

sey

Pue

rto

Ric

o

Rho

de I

slan

d

Uta

h

Ver

mon

t

Wes

t V

irgin

ia

State of Origin

Peo

ple

Mo

vin

g to

No

rth

Dak

ota

Displaying Margins of Displaying Margins of ErrorError

ACS: Residence RuleACS: Residence Rule

• What determines WHERE the Census What determines WHERE the Census counts you and your householdcounts you and your household– Decennial Census: “most of the time”Decennial Census: “most of the time”

• Considered to be a 6+ month residency ruleConsidered to be a 6+ month residency rule

– ACS: > 2 month residency ruleACS: > 2 month residency rule• So...So...

– Decennial Census counts primary Decennial Census counts primary residentsresidents

– ACS likely will mix seasonal and primaryACS likely will mix seasonal and primary

Decennial Census Decennial Census Residence RuleResidence Rule

• ““Most of the Most of the time”time”– Often referred Often referred

to as the 6+ to as the 6+ month rulemonth rule

ACS Residence RuleACS Residence Rule

SuppressionSuppression

• Due to reasons of reliability / Due to reasons of reliability / confidentiality, some tables or table confidentiality, some tables or table items for a town may be suppressed items for a town may be suppressed and not released at all.and not released at all.

• Census Bureau does not plan to Census Bureau does not plan to suppress 5-year data.suppress 5-year data.

Collapsing TablesCollapsing Tables• 2008 ACS – Means of Transportation to Work2008 ACS – Means of Transportation to Work

Table B08301Table B08301 Table C08301Table C08301

• Only the collapsed table is Only the collapsed table is available for Chittenden available for Chittenden County, VTCounty, VT

Accessing ACS DataAccessing ACS Data• American FactFinderAmerican FactFinder

– factfinder.census.govfactfinder.census.gov

Accessing ACS DataAccessing ACS DataAlso: Ranking tables with statistical Also: Ranking tables with statistical

significancesignificance

ACS 2008: ACS 2008: State State Poverty Poverty Rate Rate RankingsRankings

Tools for Using ACS DataTools for Using ACS Data

• Spreadsheet to Calculate ACS Spreadsheet to Calculate ACS Margins of Error and Statistical Margins of Error and Statistical SignificanceSignificance

• Excel file created by NY SDCExcel file created by NY SDC

– Available at SDC Clearinghouse websiteAvailable at SDC Clearinghouse website

• ACS ACS Compass ProductsCompass Products• 12 handbooks and presentations12 handbooks and presentations

– Available at ACS websiteAvailable at ACS website

The ACS WebsiteThe ACS Websitehttp://www.census.gov/acs