The PUMS product is a subsample of the ACS. The text below is from the "Accuracy of the Data" document, p. 5.
The number of households in the PUMS is a fraction of ACS given by the (inverse of) the sampling interval. What is the size of this sampling interval? I thought I read somewhere that it was about 1.3. Does anyone know?
Public Use Microdata Sample (PUMS)
Accuracy of the Data (2015-2019)
The sampling for HUs (and persons from HUs) is performed on the ACS samples of HUs for each of the years 2015, 2016, 2017, 2018, and 2019 as follows:
The PUMS HU sample file is matched to the ACS sample of persons. All persons in selected HUs were placed in the PUMS person sample.
In general, the sampling interval is set to a value such that the PUMS file is an approximate 1% sampling of the full population. For 2021, we see about 1.95 million households were interviewed in the ACS representing 142 million households. The PUMS file has about 1.56 million household records (a little more than 1% of households), so the sampling interval is about 1.25 (on average) (= 1.95 / 1.56). The specific number chosen will be based on how many households responded to the ACS in a particular year and the targeted sample size (based on the 1% of the total population calculation).
Thanks Matthew! Are the number of interviewed ACS households and the (estimated) number of actual of households published or available by year?
Also, I thought the target number of ACS households to be interviews was about 3.4 million. Has that target been lowered or were 2020 and 2021 exceptions?