Dependent Means
Dependent groups refer to some type of association or link in the research design between sets of scores. This usually occurs in one of three conditions -- repeated measures, linked selection, or matching. Repeated measures designs collect data on subjects using the same measure on at least two occasions. This often occurs before and after a treatment or when the same research subjects are exposed to two different experimental conditions.

When subjects are selected into the study because of natural "links or associations", we want to analyze the data together. This would occur in studies of parent-infant interaction, romantic partners, siblings, or best friends. In a study of parents and their children, I would want my data to be associated with my son's, not some other child's. Subject matching also produces dependent data. Suppose that an investigator wanted to control for socioeconomic differences in research subjects. She might measure socioeconomic status and then match on that variable. The scores on the dependent variable would then be treated as a pair in the statistical test.

All statistical procedures for dependent or correlated groups treat the data as linked, therefore it is very important that you correctly identify dependent groups designs. The statistics that can be used for correlated groups are the McNemar Test (two samples or times of measurement), Wilcoxon t Test (two samples), Dependent Means t Test (two samples), Friedman ANOVA for Ranks (three or more samples), Simple Repeated Measures ANOVA (three or more samples), and Mixed Factorial ANOVA (at least one factor is linked/correlated).