Stata Datetime Pseudo-Functions

Stata supports these datetime pseudo-functions functions in the global scope.

Tc

Create a value representing the number of milliseconds since the Stata epoch (01jan1960 00:00:00.000).

There are two functions: tc and tC.

To create a datetime that ignores leap seconds, try tc(01jan1960 00:00:00.000).

To create a datetime that includes leap seconds since the epoch, try tC(01jan1960 00:00:00.000).

Converting SPSS Dates and Datetimes

The tc pseudo-function can be used to normalize dates and datetimes that are imported from SPSS.

SPSS represents dates and datetimes are the number of seconds since the SPSS epoch (14oct1582 00:00:00), ignoring leap seconds. Therefore, to normalize an SPSS date or datetime, convert seconds to milliseconds and add tc(14oct1582 00:00).

generate double datetime_stata = (datetime_spss * 1000) + tc(14oct1582 00:00:00)
format datetime_stata %tc

Converting R Datetimes

Very similarly, the tC pseudo-function can be used to normalize datetimes that are imported from R.

R represents datetimes as the number of UTC-adjusted milliseconds since the Unix epoch (01jan1970 00:00:00). Therefore, to normalize an R datetime, subtract tC(01jan1970 00:00:00).

generate double datetime_stata = datetime_r - tC(01jan1970 00:00:00)
format datetime_stata %tC

Td

To create a value representing the number of days since the Stata epoch (01jan1960 00:00:00.000), try td(01jan1960).

Converting R Datetimes

The td pseudo-function can be used to normalize dates that are imported from R.

R represents dates as the number of days since the Unix epoch (01jan1970 00:00:00). Therefore, to normalize an R date, subtract td(01jan1970).

generate long date_stata = date_r - td(01jan1970)
format date_stata %td

Th

To create a value representing the number of half years since the Stata epoch (01jan1960 00:00:00.000), try th(1960-h1).

Tm

To create a value representing the number of months since the Stata epoch (01jan1960 00:00:00.000), try tm(jan1960).

Tq

To create a value representing the number of quarters since the Stata epoch (01jan1960 00:00:00.000), try tq(1960-q1).

Tw

To create a value representing the number of weeks since the Stata epoch (01jan1960 00:00:00.000), try tw(1960-w1).

Ty

To create a value representing the number of years since the Stata epoch (01jan1960 00:00:00.000), try ty(1960).

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