generating new variable based on date variable

[Roshani Patel]

Dear Stata community,

I have a variable stored as dates in the Stata format i.e 01jul1993 (I converted them from string into the correct format). However
I know want to create a new variable which organises the observations according to whether the date was pre or post 31dec1996. what would be the best command to use please? I have tried reading the manual in reference to dates/ times but I could find anything that helps with generating new variable according to the date.

Many thanks for your help,

Roshani

[Joro Kolev]

Try

gen pre31dec1996 = date<td(31dec1996)

[Nick Cox]

This example shows that true or false comparisons yield 1 if true and 0 if false.

. di mdy(10, 6, 2020) > mdy(12, 31, 1996)
1

. di mdy(10, 6, 1920) > mdy(12, 31, 1996)
0

which leads to a guess that you want something like

gen wanted = mydate > mdy(12,31,1996)

with caution for missing values as

gen wanted = mydate > mdy(12,31,1996) if mydate < .

and also thought about whether > should be >=.


You can also use the td() function. I just use mdy() because I can remember it and its exact syntax.

[Roshani Patel]

Thank you Nick and Joro, I'll give this a try. Bw Roshani