Recent research, by researchers Thomas Nechyba, Patrick McEwan, and Dina Older-Aguilar of Stanford University, examines the impact of family and community resources on student outcomes. This research was commissioned by the New Zealand Ministry of Education and can be found on their website in fulltext by using the link at the bottom of this article.

We have extracted some important summarised findings from the larger report.

The authors begin by describing a conceptual model.

"Figure 1 below, describes the major causal channels which link family and community characteristics to child outcomes. Family and parental characteristics range from genetic endowments to parental education and occupation. Given these characteristics, families make several choices that are represented in the framework by double-arrows. First, they make decisions within the household that may affect child outcomes; these include, among others, parenting styles, work habits, and financial investments in children. Second, they choose a geographic and social community, which may influence child outcomes via neighborhood effects. Third, they choose whether to become directly involved in school activities. The framework also allows that children (and perhaps parents) may choose a within-school peer group. The composition of the peer group may exert further influence over student outcomes. Ultimately, outcomes such as academic achievement and attainment are influenced by a multitude of factors relating to the families, communities, and schools. The empirical challenge facing researchers is to credibly isolate each of these effects."

Fig 1:

The authors then investigate evidence on the role of hereditary factors in determining cognitive ability, achievement, and other child outcomes and come up with four conclusions:

"First, heredity seems to play a large role in the formation of characteristics such as personality traits and cognitive abilities, with estimates of this genetic effect accounting on average for approximately 50 percent of differences across cognitive abilities in children. Second, genetic effects on scholastic achievement are somewhat similar to genetic effects on cognitive ability or IQ. Third, heredity is of increasing importance relative to childhood environment as individuals transition from childhood into adulthood and beyond. Finally, a surprisingly small fraction of differences in adulthood (0-10 percent) can on average be causally attributed to shared home environments, at least within the ranges of families studied."

The authors also examine how child outcomes are linked to features of non-shared and shared family environments and summarise the studies as follows:

"One group of studies focuses on family structure. For example, larger numbers of siblings tend to be associated with less cognitive development and lower educational attainment. But there is increasing statistical evidence that this relationship is spurious, and actually reflects the presence of other unobserved environmental or genetic factors in the home. Similarly, we find only limited evidence that the configuration of siblings (the number of girls relative to boys) affects outcomes. Another a vast literature explores the impact of parental divorce on child outcomes. While there is a consistent negative association, the roots of this are not entirely clear. Three theories might be forwarded. First, the effects of divorce might actually reflect genetic influences, although evidence is inconclusive. Second, home environments might be quite stressful prior to the dissolution of the marriage, which could be the true cause of negative outcomes, rather than the trauma of divorce; some evidence points to this interpretation, but it is difficult to separate from hereditary explanations. Third, divorce may negatively affect outcomes by reducing the family income. Evidence suggests that direct effects of income are not large, although it does appear that home relocations following divorce could account for perhaps a quarter of the negative effects of divorce. Single parenthood is also negatively correlated with outcomes, particularly among lower-income families. But the causal meaning of these results is unclear. Several explanations exist, ranging from the lower-quality home environments of single-parent families, to hereditary factors. A quite robust finding is that children have lower outcomes when their mothers choose to live with, but not marry, another partner. Again, the causal channels underlying this observed correlation may include factors such as heredity or neighborhood effects; if such variables are omitted from the analysis, then their effects are confounded with family structure. Finally, neither parental age nor non-traditional family structures such as gay parents have been found to have strong impacts on outcomes."

"Another group of studies examines how the quantity and quality of parental time investments affect childhood outcomes. The most recent evidence indicates that maternal work and child care during infancy is associated with negative behavioral and cognitive outcomes in early childhood but that these negative impacts are likely to be temporary and dissipate by middle childhood. For at-risk children, childcare is often found to improve outcomes, although these results also tend to "fade-out" as children get older. Furthermore, recent and more sophisticated research casts some doubt on whether simple indicators of child-care quality are truly associated with child outcomes. A second class of studies examines the effects of parental time investments, or lack thereof, on school-age children. Evidence from studies involving adolescent after-school care indicates that arrangements chosen by parents seem to play no large part in explaining differences in outcomes. Exceptions to this finding, however, are notable. While there is little evidence that time spent by parents monitoring adolescents within the home is important, lack of supervision after school outside the home may matter, with children in unsupervised non-home environments associating with more deviant peers and demonstrating worse outcomes in school. Furthermore, while structured after-school programs seem to have little (or possibly negative) impact on middle class children, there is evidence suggesting they may improve outcomes for at-risk children, especially for boys. A common limitation of many of these studies is their inattention to problems of selection bias."

"Apart from the literature on child care and maternal employment, a number of studies purport to show that parenting "quality" and parenting styles are related to child outcomes. While much evidence is suggestive of these influences, it is hampered by an over-reliance on Western conceptions of "good" parenting, data drawn from Western families, and the methodological challenges of selection bias and omitted variables bias."

"Finally, parental income is often correlated with child outcomes. However, the best empirical research increasingly suggests that income is generally not a strong causal channel through which child outcomes improve significantly and that policies aimed at raising family incomes are likely to have only small effects. The observed income effect probably operates through other causal channels. An important caveat is that almost all research is focused on the U.S., where lower-income households already have higher incomes than poor households of many countries. Thus, income may still play a role in conditions of extreme poverty. Furthermore, income may have more appreciable effects in some special circumstances, most notably in the very early ages of at risk-children."

The authors consider the contribution of primary and secondary schools to child development:

"A large literature attempting to link inputs such as class size and teacher attributes to student outcomes has been unable to consistently document large effects, but much of this literature is plagued by methodological problems that are likely to bias results. While some recent work has indicated that wages are more responsive to these school inputs than traditional measures of student outcomes, much of this evidence has been called into questions on both methodological and data grounds. What remains from these statistical studies is a great deal of uncertainty and a sense that the school inputs commonly measured do not contribute much to student outcomes. Given the many methodological issues, however, true experiments would be extremely valuable to the resolution of this uncertainty. Only recently has experimental evidence of this kind come to light with respect to class size. This evidence indeed suggests that the previous pessimism regarding any impact of class size on student outcomes was unwarranted. Class size, at least, does seem to contribute positively to such outcomes."

And on the effects of community resources:

"there is a feeling that certain communities are much better than others at encouraging positive childhood outcomes. Even in the absence of the types of effect hypothesized by Jencks and Mayer, communities will differ greatly in the financial resources they provide to schools, parks and other children's services. An examination of residential choice will enable us to understand the way in which parents can affect the educational resources that are available to their children. In particular, limitations on the communities that a poor family or families of particular ethnic backgrounds can easily choose may create an avenue through which parental socioeconomic characteristics will affect child outcomes. There is theoretical and empirical support for the notion that poor, low SES families will tend to cluster together in neighborhoods with few community resources. Unfortunately little empirical work has been done to directly examine the effect of residential choice on the distribution of community resources and child outcomes. "

These extracts don't tell the full picture. The full report can be found at:

The Impact of Family and Community Resources on Student Outcomes: An Assessment of the International Literature with Implications for New Zealand