Compare means in two independent groups

To compare the means in two independent groups, the t-test for independent groups can be used. In this example, a dataset/dataframe called dat contains a dichotomous variable dichotomousVariable that specifies group membership using 1 and 2 and a continuous dependent variable dependentVariable.

SPSS

T-TEST
  /VARIABLES= dependentVariable
  /GROUPS=dichotomousVariable(1,2).

R

meanDiff(dat$dependentVariable, dat$dichotomousVariable)