Difference in WAGP and INCWAGE for 2008-2012 5yr ACS sample

Looking at the ACS 2008-2012 multiyear sample for the raw PUMS data (from census website) and the IPUMS data I notice some differences in WAGP and INCWAGE.

For example:

In the census WAGP contains 47 cases with income of $20.

In the IPUMS file INCWAGE contains 32 cases of $20 and 15 cases of $21 (for a total of 47).

I assume this is from applying some adjustment factor. According to this (https://usa.ipums.org/usa/acsincadj.shtml) IPUMS does not apply the census provided adjustment factor. If that is the case what is the adjustment factor you are applying and where can I find those values? Or am I misunderstanding why there is a difference between the two variables?

Thank you,


In the multi-year ACS files, INCWAGE amounts have been standardized to the dollar value of the final year of data included in the file. In other words, INCWAGE is expressed in 2012 dollars for the 2008-2012 5-year file. The raw PUMS file does not make this adjustment for inflation; thus, small differences with the IPUMS multi-year files are expected.

Hope this helps.

Thank you for the prompt answer.

When standardizing how does IPUMS derive the adjustment factor? Is it the CPI-U-RS values provided by the PUMS data dictionary?

From 2008-2012 data dictionary:

ADJINC Year (Census Adj Factor * CPI-U-RS)

1086024 .2008 factor (1.018389 * 1.06641366)
1069920 .2009 factor (0.999480 * 1.07047619)
1061121 .2010 factor (1.007624 * 1.05309182)
1039508 .2011 factor (1.018237 * 1.02089010)
1010207 .2012 factor (1.010207 * 1.00000000)

When I use those to adjust WAGP I do not get the same numbers as in INCWAGE

And when I work backwards from INCWAGE to WAGP the adjustment factors seem to be:

2008: 1.01277

2009: 1.0164

2010: 1.03157

2011: 1.02069

2012: 1



It was recently discovered the inflation adjustment was not being applied correctly to the multi-year ACS files. The revised data will be available soon with the correct inflation adjustments.

IPUMS-USA uses the CPI-U multiplier (CPI99) to convert current dollars to constant dollars. You can see the adjustment factors in terms of constant 1999 dollars here. When standardized to constant 2012 dollars, the correct IPUMS-USA inflation factors match to two decimal places with the CPI-U-RS numbers you cite above.

Hope this helps.