How to add only one observation to a variable?

[Alexis Rodas]

Hi all,

One question, I hope that if you can help me answer it.

I want to add an observation at the end of a column. For example, I have a variable X with 10 observations and I want to add an observation so that instead of being 10 the variable has 11 observations. Is there any command that gives me this operation?

Thanks

[Igor Paploski]

Well, you can. But note that you are not adding one observation to "variable X". You are adding one observation *to your entire dataset*, of which you are only adding information for the variable X. This is do-able, but I wouldn't suggest going that way. In any case, warning is given. You could try:

set obs `=_N+1'
replace X = 1 if _n == _N

[Jean-Claude Arbaut]

Two other possibilities, for the record:

insobs 1

mata st_addobs(1)

And for the replace:

replace X=1 in L

The last L is allowed in lowercase or uppercase, I use uppercase here for readability. It can also be written with "minus one":

replace X=1 in -1