Is this a bug?

[Monica Muller]

I have Stata SE 15.1 and I noticed Stata does not convert 2/29/2011 to a date value. When I run:

scalar x1=mdy(2,28,2011)
scalar x2=mdy(2,29,2011)
dis  x1 ", " x2

It returns18686 for 2/28/2011 and a missing value for 2/29/2011. Anyone else has this problem?

[daniel klein]

Try

scalar x1=mdy(2,28,2011)
scalar x2=mdy(2,29,2011)
dis %td x1 ", " %td x2

display, if not explicitly told otherwise, uses a "smart" format to show values; specifying %td prevents this.

There was no 2/29/2011, hence Stata displays a missing value. There was a 2/29/2012, 2/29/2016, and there will be a 2/29/2020; there is nothing that Stata can do about this.

Best
Daniel

[Nick Cox]

As daniel klein implies, it's a feature. Stata knows about leap years for recent and future dates likely to be of use or interest to most users.

[Monica Muller]

Thanks. Weird enough I'm working with an organization's personnel data that shows 4 people were fired on 2/29/2011. I should doubt the accuracy of my data!