Tract Mapping with the American Community Survey Carol O. Rogers Deputy Director and CIO Rachel Justis Geodemographic 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 +/- 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

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.

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 3308.05, 3308.06, 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

A Closer Look at Kosciusko County

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.

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)

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

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

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 www.stats.indiana.edu Go to the Census Topic Page

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