By using official variables for poverty, why poverty rate is not reproduced for years 1992 and 1999?

CPS
1

By using official variables for poverty, why poverty rate is not reproduced for years 1992 and 1999?

2

As stated in the Methodology section of the IPUMS-CPS Official Poverty Rates note, “OFFPOV replicates official poverty rates for all except 5 years (1970, 1975, 1980, 1993 and 2000). The most likely reason for the discrepancies in these 5 years is due to changes in the population controls that affected weighted estimates.” (1992 and 1999 being the “income years” for the 1993 and 2000 surveys).

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