Merging multiple observations per time in panel data.

[Jon DiNatali]

Dear all,

I have a panel datatset of 74 countries with multiple daily observations. I have also four events A, B, C and D as dummy variables.

As you can see from the Table, an event may occur multiple times per one date (ex: event A in 3/17/2020). Also, multiple events may occur in one time (e.g., event B, A and C in 3/19/2020).

I would like to merge these multiple observations in order to have just one observation per date with all occuring events. For example, for 3/19/2020 event A, 1; event B, 1; event C, 1; event D, 0. For 3/17/2020, event A, 1; event B, 0; event C, 0; event D, 0

Thank you in advance!
Jon.

[Nick Cox]

In Stata terms this calls for a collapse and not a merge in the sense of the merge command.

I guess at

collapse (max) A B C D , by(country date)

[Jon DiNatali]

It works perfectly! thanks a lot.