How does STATA treat missing values of variable

Hello,

I am interested in how STATA treats missing values. For example with a database like this:

number: return:

1 0,1
2 0,5
3 .
4 0,05
5 0,1

At number 3 there is no return given. What is STATA doing with this gap? E.g. I want to calculate the mean. Does Stata take the "." as "0" or does it simply skip the gap and only use 0,1; 0,5; 0,05; 0,1 for the calculation?


Thanks!

Greetings from Germany