# Missing Values in Functions

Functions and simple arithmetic expressions treat missing values in different ways. In the expression:

`(var1+var2+var3)/3`

the result is missing if a case has a missing value for any of the three variables.

In the expression:

```
MEAN(var1, var2,
var3)
```

the result is missing only if the case has missing values for all three variables.

For statistical functions, you can specify the minimum number of arguments that must have nonmissing values. To do so, type a period and the minimum number after the function name, as in:

```
MEAN.2(var1, var2,
var3)
```