To compute the width of a time interval, subtract the ID value of the start of the next interval from the ID value of the start of the current interval. If the ID values are SAS dates, the width is in days. If the ID values are SAS datetime values, the width is in seconds.

For example, the following statements show how to add a variable WIDTH to the USCPI data set that contains the number of days in the month for each observation:

data uscpi;
   input date : date9. cpi;
   format date monyy7.;
   width = intnx( 'month', date, 1 ) - intnx( 'month', date, 0 );
datalines;
15jun1990 129.9
15jul1990 130.4
15aug1990 131.6
15sep1990 132.7

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