Frank, Elaine, Pete and others all gave spot-on assessments. Thank you!
I'm a frequent ACS PUMS user -- so I'll contribute what I've noticed as
I've compared ACS PUMS 1-Year datasets vs ACS PUMS 3-Year. The microdata at
record-level should be almost identical. You should see the same numbers of records, and
also almost identical data taken from respondent questionnaires. One exception would be:
where the coding of responses has changed (for example, the coding of
"YearBuilt" changed after 2005).
Beyond that - another exception - Bureau-assigned data elements could change. Most
notably, you can detect slight adjustments to the weights applied to individual household
and person records. This happens for the reason described by Pete - the updating of annual
Whether you're working with PUMS or summary data, the Bureau's tweaking of annual
population totals should be fairly small... for now...
The really big series break will be in 2011 - when the decennial Census reveals just how
far off those annual estimates have been, which should cascade over into a re-benchmarking
of ACS 1-Year, 3-Year, and 5-Year tables published in Fall 2011.
Consider: The Census Bureau has estimated Minnesota's 2007 population at 5,182,000.
Meanwhile, the Minnesota State Demographer and Metropolitan Council also publish annual
estimates (our official numbers for State government purposes), putting Minnesota's
2007 population at 5,263,000, or 1.6% higher. This is not a small discrepancy - and I
strongly suspect that the Bureau's efforts to make everything fit leads to seriously
unreliable housing occupancy (vacancy) rates in a lot of counties and cities.
Can I ask: Do FSCPE analysts in other states see similar discrepancies between the
Bureau's annual estimates and "alternative" (State Demographer) annual
estimates or annual projections?? Very curious to know.
-- Todd Graham
Metropolitan Council Research
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