Although the inverse relationship between the number of siblings and childrens educational performance has been well established explanations for this relationship remain primitive. One explanation resource dilution posits that parents have finite levels of resources (time energy money etc.) and that these resources are diluted among children as sibship size increases. I provide a more rigorous investigation of the dilution model than previous studies testing its implications with a sample of 24599 eighth graders from the 1988 [U.S.] National Education Longitudinal Study. My analyses support the resource dilution model in three ways. First the availability of parental resources decreases as the number of siblings increases net of controls....Second parental resources explain most or all of the inverse relationship between sibship size and educational outcomes. Finally interactions between sibship size and parental resources support the dilution model as children benefit less from certain parental resources when they have many versus few siblings. (EXCERPT)

When bigger is not better: family size, parental resources, and children's educational performance*

The resource dilution model posits that parental resources are finite and that as the number of children in the family increases, the resources accrued by any one child necessarily decline. Siblings are competitors for parents' time, energy, and financial resources and so the fewer the better. Even one sibling is too many. The author describes the general elements of the dilution position and assesses its merits for explaining the effect of siblings on one component of the educational process--tests of intellectual development. The author identifies critical flaws in recent critiques of the dilution position and concludes that dilution continues to provide the most promising explanation for why children with few siblings score higher on tests of cognitive skills than children with many siblings.

Number of siblings and intellectual development: The resource dilution explanation.

In this study we test the alternative interpretation of the effect of sibship size on childs intellectual development through sibling analysis and analysis of repeated measures of the same individuals. Both analyses are variations of change models or fixed-effects models. Change models enable us to control permanent family effects including family socioeconomic status (SES) family genetic makeup and intellectual atmosphere in the home by `differencing them out. Thus we can determine if and how much the sibship-size effect is confounded by other family influences that are difficult or impossible to control in conventional regression analysis. The data are from the [U.S.] National Longitudinal Survey of Youth (NLSY). Also included are comments by Meredith Phillips (pp. 188-92) and D. B. Downey B. Powell L. C. Steelman and S. Pribesh (pp. 193-98) and a reply by Guo and VanWey (pp. 199-206). (EXCERPT)

/pdf/sibship-size-and-intellectual-development-is-the-k7i43pxlyu.pdf

Sibship size and intellectual development: Is the relationship causal?

https://jnnp.bmj.com/content/jnnp/37/11/1290.3.full.pdf

Wechsler's measurement and appraisal of adult intelligence

This paper critiques the literature on the relationship between sibling structure and academic abilities and achievement since Cicirelli’s (1978) earlier commentary on this topic. Assessed is the extent to which the confluence model, a theoretical explanation of the influence of sibling structure, fits the empirical observations made recently on the association between sibship structure and intellectual development. Since the studies reviewed in general tend to refute the confluence model, alternative interpretations of the impact of sibling structure on academic consequences are presented. Implications for future research are also provided.

A Tale of Two Variables: A Review of the Intellectual Consequences of Sibship Size and Birth Order

Previous studies of the relationship between family size and intellectual level suggest a negative relationship between these two variables. This study presents data to show that in at least one culture the relationship between family size and ability is neither linear nor negative. In a culture where large families are the norm, children from families close to mean size have higher ability than those from families at either extreme.

Cultural modification of effect of family size on intelligence.

A comprehensive evaluation of the characteristics of students attending a public alternative school revealed marked differences between the experimental group (the alternative school) and a control group (students attending a regular public school). Alternative school students showed significantly lower achievement and ability on all measures, while manifesting notably greater approval of their teachers than did the control group. Sex differences in achievement, performance, and attitude were found among the free school sample, and these are contrasted with the pattern of sex differences in regular schools. The significance of these findings for the establishment and running of alternative schools is discussed.

https://files.eric.ed.gov/fulltext/ED089454.pdf

A. J. H. Gaite

Papers

Cultural modification of effect of family size on intelligence.

Patterns of Achievement, Attitude, and Behavior in a Tax-Supported Alternative School.