How to replace a value taking the mean of two other variables?

[Lisa Jesseee]

Hi everyone,
I am working with a panel data set, 4 waves, long format.
I created a dummy for missing values, if respondents participated in the wave, but not answered the question (dummy_`var')
Now I want to replace the missing values in each wave with the mean of the `var'[_n-1] and `var'[_n+1] if dummy_`var'==1
The variable names are: cesd numphy
This is the command I used:

foreach var in cesd numphy {

replace `var' = `var'[_n-1], `var'[_n+1]) / 2 if dummy_`var'==1

}

Somehow stata replies with "option cesd not allowed".

Does anyone have any idea what I did wrong and how I can make it work?

Kind Regards,
Lisa

[Nick Cox]

That is fantasy syntax. I don't know any language in which something like that would work as you wish. Try

replace `var' = (`var'[_n-1] + `var'[_n+1]) / 2 if dummy_`var'==1

[Lisa Jesseee]

It worked. Thanks a lot