Log:

15   data test;
16   set sasdata.chemists;
17   if jobcode = 'chem3' then description = 'Senior Chemist';
18   else description = 'Unknown';
19   run;

NOTE: There were 2 observations read from the data set SASDATA.CHEMISTS.
NOTE: The data set WORK.TEST has 2 observations and 2 variables.
NOTE: DATA statement used (Total process time):
      real time           0.02 seconds
      cpu time            0.01 seconds

Data Set(s):

Commentary:
The equality condition for a value comparison in SAS is case sensitive. The given condition is jobcode = 'chem3'. Note that "CHEM3" is not equal to "chem3" - thus, the condition is false and the description value is set to "Unknown."