Perhaps I have done something wrong, but August and December 2014 CPD show zeroes for CPSID and CPSIDP variables. For other months in 2014, for example April 2014, CPDID and CPSIDP appear just as one would expect. Any help would be greatly appreciated.
The zero values for CPSID/CPSIDP in August and December 2014 are a known error in the IPUMS-CPS data. We plan to release corrected data within the next month.
Hope this helps.