# Create a new variable based on existing data in Stata

Following are examples of how to create new variables in Stata using the `gen` (short for generate) and `egen` commands:

• To create a new variable (for example, `newvar`) and set its value to `0`, use:
` gen newvar = 0`
• To create a new variable (for example, `total`) from the transformation of existing variables (for example, the sum of `v1`, `v2`, `v3`, and `v4`), use:
` gen total = v1 + v2 + v3 + v4`

Alternatively, use `egen` with the built-in `rowtotal` option:

` egen total = rowtotal(v1 v2 v3 v4)`
Note:
The `egen` command treats missing values as `0`.
• To create a variable (for example, `avg`) that stores the average of four variables (for example, `v1`, `v2`, `v3`, and `v4`), use:
` gen avg = (v1 + v2 + v3 + v4) / 4`
Note:
Use the `/` (slash) to denote division and an `*` (asterisk) for multiplication.

Alternatively, use `egen` with the built-in `rowmean` option:

` egen avg = rowmean(v1 v2 v3 v4)`

Stata also lets you take advantage of built-in functions for variable transformations. For example, to take the natural log of `v1` and create a new variable (for example, `v1_log`), use:

` gen v1_log = log(v1)`

For additional help, see the help files within Stata (for each of the following topics, enter the corresponding `help` command):

Topic Command
Using functions `help functions`
Using `gen` `help gen`
Using `egen` `help egen`

If you have questions about using statistical and mathematical software at Indiana University, contact the UITS Research Applications and Deep Learning team.

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