Correct denominator for calculating 1970 poverty rate?

Sorry I have a lot of questions
Time-series table CL6 recommends using NT83 and NT89 for the poverty, so I used C36001 and C4C003 and C4C004 from those tables to sum the “Unrelated Individuals 14 Years+” and “Aggregate Number of Persons in Families” living in poverty.

I’m currently using the row sum of all the variables in Table NT18, “Sum of all unrelated individuals + individuals who live in families,” to calculate the denominator. Is that correct? If not, where is the correct source table for the denominator to calculate a county poverty rate?


First, I’d recommend getting your 1970 poverty data (and 1980, 1990, 2000 & 2008-2012 data) directly from time series tables rather than from source tables so you needn’t sum counts from various tables. (No need to do that work when we’ve already done it for you!) If there’s a specific reason why you need to use the source tables, please report.

Then, for the denominator, use time series table AX6. Persons for Whom Poverty Status Is Determined, which supplies the correct denominator for poverty rates for all of those years.

You’ve been so helpful - I really appreciate it.

Unfortunately we have a pre-existing dataset with our own code for county boundary changes. I tried to integrate our dataset with the AX6 ts table you recommended but have not been able to figure out the boundary changes issue. Any other recommendations to help determine the 1970 Universe Persons for Whom Poverty Status is Determined (denominator) would be greatly appreciated.

Hmm, I’m not sure why you wouldn’t be able to associate data from time series tables with your pre-existing dataset in the same way you could associate data from NHGIS source tables. In both types of tables, NHGIS includes the state and county FIPS and NHGIS codes, which are the usual ways to link county data together.

As for the “boundary changes issue”, note that the NHGIS time series for poverty data are “nominally integrated,” meaning that the tables match counties across time based only on their names with no adjustments to control for boundary changes. I.e., the counties in the time series tables should match up exactly with the counties in source tables.

It might be clearer for you if you request the time series tables in the “Time varies by file” layout instead of the default “Time varies by column” layout. This option is available on the Review and Submit page, just before you submit a data request. In the “Time varies by file” layout, each year’s data is supplied in a separate file, so you’d get the 1970 data in its own file–very similar to how you get source table data.

Finally, if you’d still like to know exactly how to construct denominators for poverty rates, that information is provided in the codebook file that comes with the AX6 time series table in a data extract ZIP file. If you scroll to the bottom of the codebook, you’ll see exactly which source variables were summed together to produce each time series statistic (including Persons for Whom Poverty Status Is Determined).

This has been immensely helpful, and I’ve learned a lot. Thank you so much!