Hi, Well, although you tried to replace the question marks, you did not actually... There is a difference between numeric and categorical missing values in SAS. The '.' character is a valid character for character variables, not a missing value. You have several options, e.g. use IF(Memory_Technology='?') THEN Memory_Technology=''; or IF(Memory_Technology='?') THEN call missing(Memory_Technology); in the data step. Note also that comparisons like IF(Processor_Speed='?') do not make much sense for numeric variables since, well, they are numeric and '?' is a character... Please consider taking some of the free SAS tutorials found at http://support.sas.com/training/tutorial/ You should find the "Free SAS Programming 1 e-Course" particularly useful. Best, PK
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