# Topcode Replacement Values IPMUS CPS ASEC **URL:** \ **Category:** CPS\ **Created:** [January 29, 2017, 3:29am UTC](https://forum.ipums.org/t/topcode-replacement-values-ipmus-cps-asec/1559 "2017-01-29T03:29:00Z")\ **Posts on this page:** 1\ **Showing post:** 1
**Author:** ![Amit\_Lazarus](https://avatars.discourse-cdn.com/v4/letter/a/8e8cbc/32.png) [@Amit\_Lazarus](https://forum.ipums.org/u/Amit_Lazarus)\ **Post date:** [January 29, 2017, 3:29am UTC](https://forum.ipums.org/t/topcode-replacement-values-ipmus-cps-asec/1559/1 "2017-01-29T03:29:00Z")
Hey IPUMS Forum, I intend to use incwage, incbus and incfarm in an anaylsis utilizing IPUMS CPS ASEC samples from 1976 to 2016. After reading through the extensive documentation on [topcoding of income variables](https://cps.ipums.org/cps/inctaxcodes.shtml) I thought it wise to harmonize the topcoding method over the time frame by replacing the topcoding method of mentioned three variables in 1976-2010 to the “[Rank proximity swap values](https://cps.ipums.org/cps/income_cell_means.shtml)” method using the “swapvalues” file. However, looking through the values of the variables in the swapvalues file some values seemed odd to me. More specifically, I fail to understand why the swapvalues file contains a non-zero value in cases that have original reported incomes that are well below the topcode threshold of the same variable in a given year. For example, in the 1988 ASEC sample serial 318 pernum 1 has a value of 24000 in incwage (combining incliongj 19,000 and oincwage 5,000). The same respondent has a value of 20,000 in incwage\_swap. Another such example would be serial 92, pernum 1, in 1976 - this respondent has a reported incwage of 37,500 which is replaced with a value of 39,000 when using incwage\_swap. Many such examples exist in the data. As far as I understand only respondents with income above or euqal to the topcode threshold were “ranked from lowest to highest and systematically swapped with other values” but according to the [topcode tables](https://cps.ipums.org/cps/income_cell_means.shtml) provided these are far below the topcode threshold of the corresponding year (199,998 [in the data it seems to be 99,999 but either way] and 50,000 respectively). Why do these cases have non-zero values in the swapvalues file? Should I use these values to replace the existing ones? What am I misunderstanding here? Any response would be much appreciated. In any case though, thank you very much for your time. --- _[View the full topic](https://forum.ipums.org/t/topcode-replacement-values-ipmus-cps-asec/1559)._