tract mapping with the american community survey

Indiana Business Research Center March 1, 2011

TRACT MAPPING WITH THE AMERICAN COMMUNITY SURVEY

Carol O. RogersDeputy Director and CIO

Rachel JustisGeodemographic Analyst


What are the ACS 5-year estimates?

First-ever released December 14, 2010

• NOT Census 2010 data

• Data collected from January 1, 2005 to December 31, 2009 and are an average for the entire period.

• Available for every state, county, city, town, place, as well as for census tracts and block groups.


The estimates cover many topics

• Education

• Industry

• Place of work

• Travel time

• Heating fuel

• Type of home (bedrooms, age, bathrooms)

• Income, poverty

• Much more …


Are the estimates any good?

• Sure, if used properly.

• Users should pay attention to the margin of error.

• If it is bigger than the estimate, use caution.

• Useful for planning and context.


Margins of error get LARGER as the size of the population gets SMALLER

Travel Time to Work for Workers 16 or Older

Indiana Marion County Ohio County

Estimate MOE +/- Estimate MOE +/- Estimate MOE +/-

Less than 5 minutes 120,195 2,379 2% 9,946 861 9% 229 77 34%

5 to 9 minutes 360,077 4,197 1% 37,285 1,675 4% 300 92 31%

20 to 24 minutes 429,050 4,303 1% 80,890 2,078 3% 470 108 23%

25 to 29 minutes 189,177 2,981 2% 35,314 1,205 3% 184 84 46%

60 to 89 minutes 101,849 2,078 2% 8,286 668 8% 268 99 37%

90 or more minutes 50,480 1,607 3% 5,276 617 12% 57 42 74%


Fast Facts about Tracts

• 1,414 tracts statewide

• Relatively equal population

• Can cross city-town boundaries, but are completely contained in a single county

• Semi-permanent, but boundaries can change

File layout example:


Northeast Marion County Tract Changes

Marion Co Tract - 2010 Marion Co Tract - 2000

Marion Co Tract - 2010 Marion Co Tract - 200020002010

These tracts were combined

These tracts were split


A Closer Look at Kosciusko County


Linguistically Isolated Spanish-Speaking Households in Kosciusko County

TractNumber of Households

Margin of Error

Confidence Interval

9617 137 75 62-212

9624 94 80 14-174

9612 79 59 20-138

9618 74 59 15-133

9619 54 51 3-105

9620 53 50 3-103

9611 47 37 10-84

9621 47 55 0-102

9613 22 23 0-45

9622 17 21 0-38

TractNumber of Households

Margin of Error

Confidence Interval

9625 16 24 0-40

9623 13 23 0-36

9610 11 22 0-33

9609 0 119 0-119

9614 0 119 0-119

9615 0 119 0-119

9616 0 119 0-119

9626 0 119 0-119

9627 0 119 0-119


• Remember that these data are based on a survey.

• The population covered by the sample ranges from 23 – 3,175 people (Average: 356)

• The number of housing units in the sample ranges from 9 – 1,043 units (Average: 151)


Where does that leave us?

• Use the data, but don’t ignore the margins of error!


Census 2010

• Counts, not estimates

• But not much data:

population,age, race, sex, housing units vacant, occupied

www.stats.indiana.eduGo to the Census Topic Page


Obtaining the data

STATS Indiana www.stats.indiana.edu

American FactFinderFactfinder.census.gov

Or send requests to [email protected]

tract mapping with the american community survey

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