Dates and times

Formats

There are three common formats across SAS, SPSS and Stata.

Date (number of days)

• SAS: MMDDYY, DDMMYY, YYMMDD, DATE
• SPSS: n/a
• Stata: %td

Time (number of seconds):

• SAS: TIME, HHMM, TOD
• SPSS: TIME, DTIME
• Stata: n/a

DateTime (number of seconds):

• SAS: DATETIME
• SPSS: DATE, ADATE, SDATE, DATETIME (as milliseconds)
• Stata: %tc, %tC

Offsets

Dates and date times use a difference offset to R:

• SAS: 1960-01-01 (3653 days)
• SPSS: 1582-10-14. (141428 days)
• Stata: 1960-01-01. (3653 days)

References

• SAS: https://support.sas.com/documentation/cdl/en/lrcon/65287/HTML/default/viewer.htm#p1wj0wt2ebe2a0n1lv4lem9hdc0v.htm

• SPSS: https://www.ibm.com/docs/en/spss-statistics/29.0.0?topic=wizard-dates-times-in-spss-statistics https://www.ibm.com/docs/en/spss-statistics/29.0.0?topic=formats-date-time

• Stata: https://www.stata.com/manuals/u25.pdf