Variance Distribution in Sibling Relationships: Advantages of Multilevel Modeling Using Full Sibling Groups

Abstract

The majority of research on sibling relationships has investigated only one or two siblings in a family, but there are many theoretical and methodological limitations to this single dyadic perspective. This study uses multiple siblings (541 adults) in 184 families, where 96 of these families had all siblings complete the study, to demonstrate the value in including full sibling groups when conducting research on sibling relationships. Two scales, positivity and willingness to sacrifice, are evaluated with a multilevel model to account for the nested nature of family relationships. The distribution of variance across three levels: relationship, individual, and family are computed, and results indicate that the relationship level explains the most variance in positivity, whereas the individual level explains the majority of variance in willingness to sacrifice. These distributions are affected by gender composition and family size. The results of this study highlight an important and often overlooked element of family research: The meaning of a scale changes based on its distribution of variance at these three levels. Researchers are encouraged to be cognizant of the variance distribution of their scales when studying sibling relationships and to incorporate more full sibling groups into their research methods and study design.

Adult Siblings Who Have a Brother or Sister with Autism: Between-Family and Within-Family Variations in Sibling Relationships

“…Not all siblings from all families participated. This aspect of selection bias may affect the variability of the data as well (Marciniak, 2017). In addition, family size is not a random variable, but may be influenced by parental and family factors not measured (Krull, 2007).…”

“…Prior research examining siblings who have a brother or sister with a developmental disability has examined one sibling dyad per family (one sibling and the brother or sister with disability). Recently, researchers have used multilevel modeling statistical techniques to examine the within and between family processes that affect sibling relationships in the general population (Gilligan, Suitor, & Nam, 2015;Jenkins, Rasbash, Leckie, Gass, & Dunn, 2012;Jenkins, Dunn, O'Connor, Rasbash, & Behnke, 2005;Marciniak, 2017) and to understand family processes in parent-child relationships (O'Connor, Dunn, Jenkins, & Rasbash, 2006). No prior research has used such methods to examine sibling relationships in the context of disability.…”