As in Rubin et al.'s research, the students were divided by social category—in this case, isolated, peer-aggressive, and average—on the basis on peer nomination on Masten, Morison, and Pellegrini's Revised Class Play measure. An attempt was again made to isolate relatively "pure" samples in each category, by classifying only those with a high score on aggression items and a low score on isolation items as "aggressive" and those with the opposite pattern as "isolated." The second independent variable was social support from school friends, nonschool friends, and siblings. The subjects were asked to choose the closest or most important person from each category and rate them on a series of items. These items measured different forms of support (e.g. companionship), which were also combined into an overall support level. High support and low support conditions were created using a median split to divide the higher and lower support scores. Children who did not have a sibling or a nonschool friend, or who did not clearly fit into the isolated, aggressive, or average social categories were screened out, leaving 200 subjects in the study. The dependent variables in the study were self-report scales measuring loneliness, depression, and general self-worth, and parent and teacher checklists with items measuring anxiety and immaturity–passivity.
