The independent variable determines which groups the scores are in. In experiments, the experimenter determines which group or condition the subject is in. A related set of groups is the independent variable. Sometimes characteristics of the observation determines group. For example, sex is a variable with two levels or groups: male and female. Be careful not to confuse groups with variables. Remember that a variable must vary; that is, there must be different levels or groups for an independent variable.
This is a special case for asking whether a single group differs from some prior value.
© 2002, Gary McClelland