Published: June 5, 2018

Download: Life Course Centre Working Paper: 2016-15


Chris Ryan and Anna Zhu.

Non-Technical Summary:

We explore the extent to which starting primary school earlier by up to one year can help shield children from the detrimental, long-term developmental consequences of having an ill or disabled sibling. Primary school entry age is an adjustable policy tool. Over the last few decades, the legal minimum age of school start has gradually increased in most developed nations. Deming & Dynarski (2008) attribute roughly a quarter of this upward drift in the age at which children are allowed to start primary school in the United States, for example, to changes imposed by the state. This policy direction has broadly been motivated by the intention to increase the school readiness of children.

The actual benefits of delaying school start are not, however, unambiguously positive. Particularly for disadvantaged children, spending additional time out of school may in fact be unhelpful compared to starting school at an earlier age. Importantly, children who delay their school entry may linger in environments whose quality is positively correlated with their parent’s time and money resources. Entering school earlier, by contrast, may work to equalise the opportunities to learn and interact because it asymmetrically increases a relatively disadvantaged child’s exposure to educational stimulation.

We have chosen to focus on the presence of an ill sibling rather than on more conventional measures of disadvantage. Most of the literature evaluating major early childhood programs use the more conventional measures of income poverty or the child’s own human capital endowments and find that the benefits for children’s cognitive achievement scores tend to fade-out quickly. These programs usually target deeply disadvantaged children whose experiences of hardship are often multi-faceted and continue to affect them long after they complete the programs. The depth of their disadvantage may thus undermine the ability of these children to capitalise on the initial gains from program participation. In contrast, the existence of poor health in the sibling may be a less entrenched source of disadvantage than poverty or the study child’s own low IQ. Even though poor health in the sibling may entail and partly originate from broader experiences of economic and social disadvantage, there is also an element of bad luck when it comes to how poor sibling health is distributed among families.

Using data from the Longitudinal Study of Australian Children, we find that Australian children who have a sibling in poor health persistently lag behind other children in their cognitive development – but only for the children who start school later. In contrast, for the children who commence school earlier, we do not find any cognitive developmental gaps. The results are strongest when the ill-health in the sibling is of a temporary rather than longer-term nature. However, we find mixed impacts on the gaps in non-cognitive development.


July 20, 2016