Frequently Asked Questions

Question: What criteria are used to determine if a person is low or moderate income?

Answer: For CDBG, a person is considered to be of low income only if he or she is a member of a family whose income would qualify as "very low income" under the Section 8 Housing Assistance Payments program. Unrelated individuals are considered as one-person families for this purpose. Generally, these Section 8 limits are based on 50% of area median income (AMI). Similarly, CDBG moderate income relies on Section 8 "lower income" limits, which are generally tied to 80% of AMI.

Question: What do all the column headers mean?

Answer: All of the column headers are explained in the American Community Survey 5-Year 2006-2010 Low and Moderate Income Data Dictionary.

Question: Can I link the ACS Low and Moderate Income Summary Data with other Census data?

Answer: Yes! The ACS Low and Moderate Income Summary Data (LMISD) includes the GEOID, which is the key field used to link the geography to all 2010 Census data tables, as well as Census geographies.

Question: Why does the total of the LOW, LOWMOD and LMMI values sometimes add up to more than the LOWMODUNIV total?

Answer: Each of these sets of data are cumulative. LOW contains the count of all persons below the 50% income level; LOWMOD contains the count of all persons below the 80% income level; and LMMI contains the count of all persons below the 120% income level. Therefore, if you add LOW+LOWMOD+LMMI, you would double count the persons who are moderate income, and triple count the persons who are low income.

Question: Can I get LOWMOD data at the split-block level?

Answer: The new ACS-based LMISD datasets are in a slightly different geographic format from the previous datasets based upon the decennial Census. The principal reason for this change is due to lower data confidence interval at the smaller geographies. Prior versions of the LMISD were based on the long form of the decennial Census, which was sent to 1 in 6 households (17%). The American Community Survey is administered continuously, with a target of approximately 1 in 40 households (2.5%) each year. ACS estimates used for the LMISD combine 5 years of surveys, meaning that the effective sample size is 1 in 8 households (12.5%). The fact that the ACS has a smaller sample than the decennial Census long form means that resulting estimates have larger confidence intervals and are less precise, especially for small areas. Therefore, the smaller “split-block groups” will not be available as they have in the past. The split-block group or Summary level 090 geography is one of the smaller geographic building blocks, which can be utilized to reconstruct other higher level geographies that are otherwise incompatible with one another, such as places and block groups. In lieu of providing the Summary level 090 geography, HUD is publishing LMISD datasets at both the Summary level 150 (Block Groups), and at the Summary level 160 (Incorporated Cities and Census-designated Places). Grantees are advised against defining a single service area using a combination of both Summary level 150 data and Summary level 160 data because the geographies may have overlapping areas, thus double counting residents.

Question: Why are there duplicate block groups in the summarized data files?

Answer: Previously, the Summary level 090, split-block group, layer allowed HUD to associate a portion of a single block group with one grantee, and another portion of that same block group with a different grantee. However, since the split-block group layer is not provided, HUD now creates the LMISD block group file with duplicate block group records for each block group that overlays one or more grantee jurisdictions, thus associating that block group with each of the grantees who share it. Therefore, when performing analyses on the block group data, it is important to address this by either removing duplicate records for the same block group or establishing one-to-many data relationships, as appropriate.

Question: Since the block group level data does not designate place and county subdivisions how can I find which block groups are in a particular city, town or village?

Answer: The 2010 Census Block Map Series were produced by the Bureau of Census to support the 2010 Decennial Census data release. These maps display tabulation geography down to the census block level. These large-scale maps show the boundaries and numbers for all census blocks within an entity. In addition to state and county, these maps show the boundaries, names and codes for American Indian areas, Alaska Native areas, Hawaiian home lands, county subdivisions, places and census tracts. The maps can be found at: https://www.census.gov/geo/maps-data/maps/block/2010/.