mean of single variable and multiple variables

[Seungmin Lee]

I try to find mean values of a few different variables at the same time,

The problem is, STATA gives different mean values when I type commands differently.

For example, I try to find mean values of v8, v10, v12 of deck 2, hh82

If I type "mean v8", it gives 240.9 from 2381 observations

If I type "mean v12", it gives 329.0 from 3869 observations,

However, if I type "mean v8 v12", it gives 240.1, 363.9 from 2380 observations, which are different from previous two mean values.

Why does it happen? How should I handle this?

[Jia De Gedeon Lim]

Hi Seungmin,

So that's your answer. Stata ignores missing values when computing means. The command "mean v8 v12" tells Stata to evaluate the mean of variable v8 & v12 individually over the observations for which BOTH v8 and v12 are non-missing. So mean v8 v12 is working on a subset of 2380 observations for which both v8 and v12 are non-missing.