1. Tract Mapping with the American Community Survey
Carol O. Rogers
Deputy Director and CIO
Rachel Justis
Geodemographic Analyst

2. 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.

3. The estimates cover many topics
Education
Industry
Place of work
Travel time
Heating fuel
Type of home (bedrooms, age, bathrooms)
Income, poverty
Much more …

4. 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.

5. 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
+/-
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
80,890
2,078 3%
470
108
23%
25 to 29 minutes
189,177
2,981
35,314
1,205
184 84
46%
60 to 89 minutes
101,849
8,286
668 8%
268 99
37%
90 or more minutes
50,480
1,607
5,276
617
12% 57 42
74%
ACS margins of error are for the 90% confidence level

6. 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:
Census tracts are small, relatively permanent areas that normally follow visible features
Designed to be relatively homogeneous units with respect to population characteristics, economic status, and living conditions, census tracts average about 4,000 inhabitants. Generally, census tracts have between 2,500
and 8,000 residents.

7. Northeast Marion County Tract Changes
2010
2000
These tracts
were combined
When new census tracts (splits) occur within an established set of census tracts, the Census Bureau recommends
retaining the original four-digit census tract number and adding a two-digit decimal suffix. As a result, Census Tract 101 may be split into Census Tracts , , and so forth, depending upon how many new census tracts are created. If a census tract identified by a suffixed number is subsequently split, the census statistical areas committee usually drops the existing suffix and utilizes the next available suffixes.
These tracts
were split

8. A Closer Look at Kosciusko County

9. Linguistically Isolated Spanish-Speaking Households in Kosciusko County
Tract
Number of Households
Margin of Error
Confidence Interval
9617
137 75
62-212
9624 94 80
14-174
9612 79 59
20-138
9618 74
15-133
9619 54 51
3-105
9620 53 50
3-103
9611 47 37
10-84
9621 55
0-102
9613 22 23
0-45
9622 17 21
0-38
Tract
Number of Households
Margin of Error
Confidence Interval
9625 16 24
0-40
9623 13 23
0-36
9610 11 22
0-33
9609
119
0-119
9614
9615
9616
9626
9627
A zero estimate means that no respondent in the survey had that specific characteristic for a particular geographic area. Because the ACS is a survey that is sent to a subset of the population, it is possible that there are persons in the population who possess that characteristic that were not in sample. To reflect this possibility, the ACS includes a margin of error on the zero estimate to help inform users that the true value may be as large as the margin of error with a 90% probability.

10. 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)

11. Marion County tract had estimate of $11,800 with a margin of error of $53,300 for +/-450%.
Another Marion county tract had an MOE of $84,000. Overall, 14 tracts statewide had MOEs > $50,000, with almost half of those in Marion County

12. Where does that leave us?
Use the data, but don’t ignore the margins of error!

13. population, age, race, sex, housing units vacant, occupied
Census 2010
Counts, not estimates
But not much data:
population, age, race, sex, housing units vacant, occupied
Go to the Census Topic Page

14. STATS Indiana www.stats.indiana.edu
Obtaining the data
STATS Indiana
American FactFinder
Factfinder.census.gov
Or send requests to