What explains the smaller sample in the 2002 ACS (1-year estimates)? I see the IPUMS page “Description of IPUMS samples” (https://usa.ipums.org/usa/sampdesc.shtml#us2002a) documents the following sample rates between the years 2001-2004:
2001: 1-in-232
2002: 1-in-261
2003: 1-in-236
2004: 1-in-239
I am doing some work with these samples, and see that when we look at observations age 18+, this amounts to approximately 50,000 fewer households (~90,000 people) sampled in 2002 than 2001 or 2003. I have not been able to find any explanations on this forum or other resources, so I am curious if there is a documented reason behind this?
The 2009 Design and Methodology report describes this period (2000-2004) as a “demonstration stage”:
During the demonstration stage (2000 to 2004), the Census Bureau carried out large-scale, nationwide surveys and produced reports for the nation, the states, and large geographic areas. The full implementation stage began in January 2005, with an annual HU sample of approximately 3 million addresses throughout the United States and 36,000 addresses in Puerto Rico. And in 2006, approximately 20,000 group quarters were added to the ACS so that the data fully describe the characteristics of the population residing in geographic areas.
More specifically regarding sampling in 2002, this report on the operational feasibility of the ACS makes the following note:
The workloads shown for the 2002 ACS dropped somewhat from 2001 levels because of a planned decrease in the sample within the ACS test sites and an additional adjustment to the Supplementary Survey sample…The ACS test sites were originally sampled at a high rate that allowed three-year averages to be compared to the Census 2000 at the tract and county level. Starting in 2002 the sample size in the ACS test sites is at the level required for five-year averages. Budgetary constraints required an additional cut to the sample of the 2002 Supplementary Survey. The entire July panel was dropped, plus the CATI and CAPI nonresponse followups were dropped from the June panel.
Due to significant differences between the demonstration stage and full implementation, especially the absence of group quarters individuals, particular caution should be used with estimates from this early period of the ACS.
Thank you Ivan, I appreciate the fast response!
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