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):