Standardizing a variable

Standardizing a variable means subtracting its mean from every data point in the data series, and the dividing the resulting numbers by the variable’s standard deviation. The result is a variable with a mean of 0 and a standard deviation of 1.

In this example, a dataset/dataframe called dat contains a continuous variable called independentVariable.

SPSS

This command orders descriptives, but the /SAVE subcommand also saves the standardized values. These are then given the original variable name prepended by Z, so in this case, ZindependentVariable:

DESCRIPTIVES  VARIABLES = independentVariable
 /SAVE.

R

This stores the standardized values in a variable called standardizedIndependentVariable:

dat$standardizedIndependentVariable <-
  scale(dat$independentVariable);

In R is also easy to center a variable around its mean. The following command stores the centered values in a variable called centeredIndependentVariable:

dat$centeredVariable <-
  scale(dat$independentVariable, scale = FALSE);