Young in Class: Implications for Inattentive/Hyperactive Behaviour of Canadian Boys and Girls Revision March, 2013 Kelly Chen, Nicole Fortin, Philip Oreopoulos and Shelley Phipps This research is being conducted as part of the Canadian Institute for Advanced Research (CIFAR) Programme on Social Interactions, Identity and Well-Being. The NLSCY data were access through the Atlantic Research Data Centre; we thank Heather Hobson for vetting our output. 1 Abstract Are Canadian children who are young relative to their class-mates more likely to exhibit inattentive/hyperactive behaviours? If so, are there gender differences in the extent to which this is true? Do the effects on inattentive/hyperactive behaviours of starting school relatively young persist into adolescence?; and, if so, can this help to explain gender differences in educational outcomes, behaviours and aspirations of Canadian youth? Using data from the Statistics Canada National Longitudinal Survey of Children and Youth, we apply two research strategies to address these questions. A ‘difference in difference’ design compares children who are the same age in months, but live in provinces and/or time periods with different school start dates. A ‘regression discontinuity’ design compares scores for children living in the same province who were born just born and just after the relevant school entry cut-off. Both approaches find more inattentive/hyperactive behaviour for children who are young in class, especially if the child was more inattentive/hyperactive prior to school entry. When we control for child inattentive/hyperactive behaviour at ages 2/3, we find that being young in class exacerbates an underlying tendency toward inattentive/hyperactive behaviours and thus pushes more boys than girls into clinical levels. These effects persist into early adolescence and may contribute to gender differences in other early adolescent school-related behaviours, aspirations and outcomes. 2 Recent research emphasizes the idea that human capital acquisition is a cumulative process (e.g., Cunha and Heckman, 2009; Currie, 2011; Conti and Heckman, 2012; Heckman, Stixrud and Urzua, 2006). Both cognitive and non-cognitive capacities developed early in the educational process can enhance the productivity of later education; moreover, higher capacity in one dimension is argued to complement the capacity to grow in another (e.g., an attentive child can learn to read more easily). Thus, experiences at the very start of their school lives can have long-run repercussions for children’s eventual educational success. Attention of both scholars and popular media (e.g., Fortin et al., 2012; Gurian, 2009; Sax, 2007) has also recently been drawn to the fact that girls’ academic achievement has now surpassed boys.’ Young women now comprise 60 percent of the undergraduate population in most Canadian universities. In 2008, 36.5 percent of young Canadian women aged 25 to 29 had university degrees compared to 24.1 percent of young men (Drolet, 2011). In this paper, we explore the possibility that part of the explanation for boys’ lagging academic motivation and achievement may originate in the early years at school. For example, if boys come to dislike school a little less at the very beginning, this can snowball over the years into significantly different educational attitudes/behaviours/outcomes. In particular, we focus on inattentive/hyperactive behaviour as one important aspect of non-cognitive development that has become more of a problem in recent decades, matters for educational attainment and has big gender differences early in life. 1 1 U.S. data (e.g., Akinbami, et al., 2011; Child Trends, 2012; Garfield, 2012) show increased prevalence of Attention Deficit Hyperactivity Disorder (ADHD), a clinical level of the kind of behavior we study here. Attention- Deficit/Hyperactivity Disorder (ADHD) is among the most commonly diagnosed behavioural disorders for children in many countries (Elder, 2010; Faraone, et al., 2003; Skounti et al., 2007). ADHD is a developmental, neurobiological condition defined by the presence of severe and pervasive symptoms of inattention, hyperactivity and impulsivity which must be exhibited over a period of at least 6 months, before the age of 7 and in at least two contexts such as home and school (Daley and Birchwood, 2010; Loe and Feldman, 2007). Secular trends are hard to identify given changes in diagnostic practices, but increases in prevalence are apparent over the past 40 years (Perrin 3 A significant body of research indicates that children who are less attentive or more hyperactive experience problems with human capital acquisition (see, for example, Daley and Birchwood; 2010 or Loe and Feldman, 2007 for reviews of the medical/psychological literature). For example, they score lower on math/reading tests, are more likely to have behavioural problems at school and/or to repeat a grade (Loe and Feldman, 2007). Most of this research has focussed on young school-aged children, but, negative implications of hyperactivity on academic performance have also been found for adolescents (Birchwood, 2010) and even college students (e.g., Frazier, et al., 2007). However, not all studies have adequately controlled for the possibility that, for example, the home environments of children with and without ADHD may differ (e.g., in terms of parental income, health, etc).2 Thus, important recent economic contributions to the literature include Currie and Stabile (2006) and Fletcher and Wolfe (2008) who confirm the negative impact of ADHD on academic achievement in models exploiting sibling differences in samples representative of the population. From our perspective, an important finding is that that academic problems are present even for children with only some symptoms of inattention/hyperactivity (i.e., they are a bit more wiggly/boisterous/distractible than other children), even if ADHD is not diagnosed or even if hyperactivity is well below clinical levels (Currie and Stabile, 2006). Although it was once thought that ADHD symptoms disappeared during adolescence, a growing body of research indicates that hyperactive/inattentive behaviours continue into adulthood (Wilens, Biederman and Spencer, 2002). For example, there are follow-up studies of et al., 2007). Current estimates suggest worldwide ADHD prevalence ranges between 4 and 10 percent (Faraone, et al., 2003; Skounti et al., 2007; Spencer et al., 2007). 2 This can be a particular problem for studies of clinical samples of children being treated for ADHD (see Bauermeister et al, 2007, Table 1). 4 clinical populations that demonstrate persistence of symptoms over time (Biederman et al., 1998; McGee et al., 1991). And, longitudinal research also finds that early childhood inattention/hyperactivity has negative implications for academic outcomes both in adolescence (Fletcher and Wolfe, 2007; Currie, et al., 2010) and even in adulthood (e.g., Daley and Birchwood, 2009; Fletcher, 2013; Frazier et al, 2007). There is surprisingly little ADHD research discussing gender differences. Indeed, since boys are much more likely to be treated for ADHD, clinical studies have a particularly male focus. However, population estimates indicate that many more girls exhibit symptoms of ADHD than are diagnosed (Gerson and Gerson, 2002); and, ‘ADHD females share with their male counterparts prototypical features of the disorder (e.g., inattention, impulsivity, and hyperactivity), [and] high rates of school failure’ (Wilens, et al., 2002). This is of particular interest for our study with its focus on gender and on inattentive/hyperactive behaviours that fall short of clinical ADHD. Another branch of research upon which we build presents evidence that children who are young within grade at school are more likely to be diagnosed with ADHD (e.g., Elder, 2010; Evans, 2010; Morrow, et al, 2012). Using U.S. data., Elder, for example, finds that 8.4 percent of children born in the month prior to the state cut-off for kindergarten eligibility are diagnosed with ADHD compared to 5.1 percent for those born in the month after. Morrow et al., 2012 report similar findings for B.C. Although these authors focus on the implications of being young in class for diagnosis of ADHD, we argue that it is also plausible that being young in class actually increases inattentive/hyperactive behaviour (though not necessarily to clinical levels). Since young in class children can be almost one full year younger than some of their peers, 5 expectations for paying attention, sitting still, etc might be hard to achieve, leading them to ‘tune out’ or ‘burst out’ with more boisterous behaviour both at school and at home. Although the effects of hyperactivity are known to persist over the long-term, there is some dispute in the literature about how long-lasting we might expect effects of being relatively young in class to be. Bedard and Dhuey (2008) present evidence for a variety of countries (and the Canadian province of BC) that relative school start age effects persist into the adult years; Smith (2007), using the same BC data set, also finds evidence of effects persisting into the high school years. On the other hand, Bertrand and Pan (2011) argue, using U.S. data, that effects dissipate; Dobkin and Ferreira (2010), again in the U.S. context, argue that there are no long- term implications for adult labour market outcomes since younger children, on the one hand, have poorer academic outcomes during their school years, but, on the other hand, are more likely to pursue