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SPSS FAQ
How can I change a string variable into a numeric variable?

Sometimes you have a data set with a variable that appears to be a numeric variable, perhaps because it has numeric values, but is really a string variable. Because you cannot perform most statistical operations on a string variable, you may want to turn the string variable into a numeric variable. Consider the following data set.

data list list / id * name (A5) score (A5) gender (A2).
begin data
1 "Beth" "57" "f"
2 "Bob" "65" "m"
3 "Barb" "70" "f"
4 "Andy" "45" "m"
5 "Al" "80" "m"
6 "Ann" "81" "f"
7 "Pete" "66" "m"
8 "Pam" "60" "f"
9 "Phil" "70" "m"
end data.

Because the variable score is a string variable, we cannot calculate a mean, etc. for this variable. There are several ways that you can change a string variable into a numeric variable. One way is to use the number function with the compute command. To do this, you need to create a new variable using the compute command. To use the number function, you need to enclose the name of the string variable and a format for the new numeric variable.

compute score1 = number(score, F2).
execute.

Now that we have a the scores in a numeric variable, we can calculate some descriptive statistics.

desc var = score1.

Descriptive Statistics

	N	Minimum	Maximum	Mean	Std. Deviation
SCORE1	9	45.00	81.00	66.0000	11.24722
Valid N (listwise)	9

Another way to convert string representations of numeric values into a numeric variable is to use the recode command with the convert option.

recode score (convert) into score2.
execute.

In some cases, you may have non-numeric symbols in your string variable that stand for numeric values. In that case, you can also convert them into numbers within this command, as shown below.

recode score ('  ' = -9) (convert) ('-' = 11) ('&' = 12) into newvar1.
execute.

If you have only a few values in your string variable, you could use the recode command and create a new numeric variable. Let's convert the string variable gender into a numeric variable.

recode gender ('m' = 1) ('f' = 2) into ngender.
execute.

Another way to recode gender, or any string variable for which you want a numeric representation of the categories, is to use the autorecode command.

autorecode gender /into ngen.
execute.

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