UC Berkeley

During adolescence older siblings who are close in age may serve as examples to emulate or become different from. Key features of the sibling relationship that may promote similar sibling outcomes include sibling intimacy, older sibling support, younger sibling image of the older sibling, and self-reported social learning and differentiation. The goal of this dissertation was first to (a) examine whether older sibling support represents a single or multiple factors and then to (b) investigate which aspects of the sibling relationship predict younger siblings' membership in one of four achievement groups. Data was collected from 288 younger siblings (YS) in ninth and tenth grade. Participants reported their own and their older sibling's (OS) grades and completed measures of sibling intimacy, OS support for YS academic plans, YS image of OS, social learning, and differentiation. They also completed demographic and family data including family cohesion and parent expectations of achievement. First, factor analysis results indicated that OS support for YS academic plans represented four distinct factors: Encouragement, Goal Setting, OS Academic Engagement, and Involvement. Second, four sibling achievement groups were created based on a median split of grades in order to determine which of these factors as well as other sibling relationship variables best predicted younger siblings' achievement in the context of their older sibling's achievement: OS high-YS high (HH), OS high-YS low (HL), OS low-YS high (LH), and OS low-YS low (LL). Discriminant analyses indicated that younger siblings were most often correctly classified (55% correct) into their corresponding achievement group when GPA rather than a global rating of grades was used as a measure of academic achievement. The strongest predictor of YS achievement was OS academic engagement, followed by parent expectations of achievement and differentiation. Classification was most accurate (81%) when older siblings were high achievers and when parent expectations of achievement were not low and most inaccurate (37-46%) when older siblings were low achievers. These results provide evidence that older siblings' academic engagement is a key aspect of older sibling support that relates to younger siblings' academic achievement and highlight the importance of both sibling and family variables in influencing younger siblings' achievement. Given that the sibling relationship is both nested within a family and has distinct influences, future research should use a multilevel approach with data from multiple informants in order to distinguish between family, parent, and sibling influences and examine the relative contributions of each of these relationships.