Time discrepancies

[Linda Shuk]

Hi STATA Experts,

I could not figure out why Stata changes minutes and seconds when I try to create a common datetime variable based on the existing datetime variables using some condition.
For example, I use this part of code to create a new variable <rand_datetime>

gen rand_datetime=randold_dt if rand_before11nov==1
replace rand_datetime=rand_dt if rand_before11nov !=1
format rand_datetime %tc

After running the above code for some records time (minutes and seconds do not natch with the original one)
Could someone shed a light on this problem?
I attached a screenshot of partial result and particular highlighted one as an example of discrepancy.

Thanks

[Joseph Coveney]

Try

generate double rand_datetime = randold_dt if rand_before11nov == 1

and see if that helps.

[Nick Cox]

Amplifying the on-target answer of Joseph Coveney I note that the advice that you must use double for datetimes appears repeatedly in

help datetime

See also https://journals.sagepub.com/doi/pdf...6867X251341416 which may be interesting or useful as an overview of this territory.

[Linda Shuk]

Brilliant! This works well. Thanks a lot Joseph and Nick. Very helpful as always.