School Start Age and Hyperactivity in Canadian children

1. School Start Age and Hyperactivity in Canadian children Kelly Chen, Nicole Fortin, Philip Oreopoulos and Shelley Phipps

2. This research is being conducted as part of the Canadian Institute for Advanced Research (CIFAR) Programme on Social Interactions, Identity and Well-Being • We thank CIFAR for funding support and Heather Hobson of the Atlantic Research Data Centre for vetting our output

3. Motivation • Attention-deficit/hyperactivity disorder (ADHD) is the most commonly diagnosed behavioural disorder among young children in many countries (Elder, 2010; Faraone, et al., 2003; Skounti et al., 2007) • Secular trends hard to identify given changes in diagnostic practices, but dramatic increases apparent over past 40 years (Perrin et al., 2007) • Current estimates suggest worldwide ADHD prevalence between 4 and 10 percent (Faraone, et al., 2003; Skounti et al., 2007; Spencer et al., 2007)

4. Consequences of ADHD in Educational Context • Score lower on math/reading tests • More likely to repeat a grade • More behavioural problems at school (Currie and Stabile, 2006; Loe and Feldman, 2007) ** These present even for children with some symptoms of hyperactivity, even if not diagnosed or at clinical levels

5. School Start Age and Hyperactivity • Elder (2010) presents evidence that children who are young within grade at school are more frequently diagnosed with ADHD • 8.4 percent of those born in the month prior to state cut-off for kindergarten eligibility compared to 5.1 percent for those born in the month after • Teacher assessments of symptoms had strong association with relative child age; parent assessments only a weak association • Sciotto et al., 2004 find that teachers are more likely to refer boys for ADHD

6. Misdiagnosis not the Whole Story? • Children who are young in class may feel frustration, be more tired, like school less, be less engaged and so become restless or inattentive? • We’ll look at impact of school start age on symptoms of hyperactivity well below normal ‘clinical’ levels, which can still connect to poorer educational outcomes (Currie and Stabile, 2006; Chen et al., 2011)

7. Research Questions • Are Canadian children who are young relative to their class-mates more likely to exhibit symptoms of hyperactivity than their classmates? • If so, are there gender differences in the extent to which this is true? • Is there an impact of being young in class even controlling for pre-school hyperactive symptoms?

8. School Entering Rules in Canada • Across provinces, children are admitted to school once a year, with eligibility determined by a single cut-off date • Kindergarten not compulsory, but is ‘normal’ • Compliance rates very high (over 95% of children in ‘correct grade’ in K through 3 • Each province (school board, in AB/SK) has the flexibility to set school entry dates • Range from early September to March during1987-2004

10. Two Research Strategies • “Regression Discontinuity” • Compare children within provinces who are born just before or just after school start date (e.g., Nov/Dec versus Jan/Feb babies, when Dec 31 is cut-off) • “Difference in Difference” • Compare children of exactly the same age in months living in provinces with different start dates so that one may be ‘youngest in class’ while another is ‘oldest in class’ (e.g., Nov babies who are ‘young’ with Dec 31 cut-off but ‘old’ with a September 30 cut-off)

11. Data • Statistics Canada’s National Longitudinal Survey of Children and Youth (NSLCY) • First cycle begins in 94/95 with data collection occurring at two year intervals • Pool data from cycles 1 through 8, 1994 through 2008

12. Basic Analytical Sample • Children aged 4 -9 years • In Kindergarten through Grade 3 • Who attended public (or publically funded) schools • With parent report of province of residence when 4/5 years old and have not moved inter-provincially since

13. Hyperactivity Index • “How often would say this child …” • “Can’t sit still or is restless” • “Is easily distracted, has trouble sticking to an activity” • “Can’t concentrate, can’t pay attention for long” • “Is impulsive, acts without thinking” • “Has difficulty waiting for his turn in games or groups” • “Cannot settle to anything for more than a few minutes” • “Is inattentive” 1= Never or not true; 2= Sometimes or somewhat true; 3=Often or very true Score ranges from 0 to 14

14. Research Strategy I. • Regression Discontinuity Hyperi = α+ τ Youngi+ γ f(bdi-ci) + β1 Provincei + β2 Cyclei + β3 Gradei + λ Xi + εi • Compare children within a province and grade who are born ‘just before’ and ‘just after’ the legal cut-off date

15. Illustration of RD approach

17. Boys and Girls Compared

19. Research Strategy II. • Compare children of exactly the same age in provinces with different cut-offs, so that in one province, the child is ‘young in class’ while in the other, he/she is ‘old in class’ • If born in 6 months prior to provincial cut-off

21. Hyperactivity Scores for April to June babies with Oct to Dec babies

22. DID Estimation All regressions control age in months (have done everything using higher order terms in age in months with no change in findings)

24. Robustness Checks • Exclude children not in correct grade (very few; no noticeable change in results) • Include all children (e.g., in private schools – same results, only very slightly smaller estimated magnitudes) • Check strategic timing of births? No apparent pattern • Other reasons for ‘jumps’ at cut-off date? Regress each covariate on ‘young’ (only mother higher education marginally significant – positive)

25. Quebec BC NS Ontario

26. Research Questions about Pre-school hyperactivity • Does starting school young still increase hyperactivity once we control for pre-school symptoms? • Do more hyperactive children have a particularly difficult time being young in class? • Are there gender differences?

28. Control for pre-school hyperactivity in both RD and DD models • Use longitudinal sample of children observed at age 2/3 as well as at ages 4 through 9 • Consider both linear pre-school hyperactivity scale and ‘high hyperactivity’

33. Conclusions • Children who are young relative to classmates exhibit more symptoms of hyperactivity, as assessed by parents • This is true, even controlling for pre-school hyperactivity • Children with higher levels of pre-school hyperactivity (more likely to be boys), have a particularly difficult time

34. Policy? • Staggered school entry (twice per year?) and/or extra accommodation for relatively young children? • More recess? • Finland model (formal schooling starts at age 7)

35. Thanks!

36. Hyperactivity Score by Province

37. Hyperactivity More Persistent for Boys than for Girls