All cards were checked individually by the electronic 

 statistical machine for the presence of all necessary punches 

 and the absence of punches which are inconsistent with the 

 questionnaire and coding. Checks were made to assure conformity 

 with all skip patterns as well as the correct relationship of 

 various types of information to each other in all cases where 

 such relationships were interdependent. In every case where in- 

 consistencies were found, each card was corrected by reference 

 to the questionnaire it represents and the corrected cards were 

 re-run through all previously made consistency checks. 



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