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 2

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) 3

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 4

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 5

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) 6

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? 7

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 8

9. Cut-Off Dates for School Entry Sep. 1Sep. 30 Dec. 1 Dec. 31 Last Day of Feb. Mar. 1 AB Calgary School District QC NS MB(87- 96) BC SK MB(97-04) ON NB NL AB Lethbridge Red Deer Lloydminster Grande Prairie Wetaskiwin AB Medicine Hat School District AB Edmonton School District 9

10. Two Research Strategies 10  “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 11

12. Basic Analytical Sample 12  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 13

14. Research Strategy I.  Regression Discontinuity Hyper i = α+ τ Young i + γ f(bd i -c i ) + β 1 Province i + β 2 Cycle i + β 3 Grade i + λ X i + ε i  Compare children within a province and grade who are born ‘just before’ and ‘just after’ the legal cut- off date 14

15. Illustration of RD approach 15

16. Table 1. Regression Discontinuity Estimates of the Effect of School Starting Age on Hyperactivity Scores. 4 to 9 year olds. Sample Mean (1)(2)(3)(4)(5)(6) Young0.530** (0.231) 0.477** (0.226) 0.573*** (0.199) 0.562*** (0.199) 0.661*** (0.150) 0.714*** (0.149) 2 month window N=8293 4.099xx 3 month window N=12491 4.100xx 6 month window N=24878 4.095xx + Covariatesxxx 16

17. Boys and Girls Compared 17

18. Table 2. Regression Discontinuity Estimates of the Effect of School Starting Age on Hyperactivity Scores. Boys vs Girls. BoysGirls Mean (1)(2)(3)Mean(4)(5)(6) Young0.681* (0.345) 0.935*** (0.295) 0.910*** (0.217) 0.252 (0.25) 0.173 (0.220) 0.523*** (0.178) 2 month window 4.55x3.64x 3 month window 4.55x3.61x 6 month window 4.62x3.57x + Covariatesxxxxxx N41336184122704032595511876 18

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 19

20. Some Provincial Variation in ‘Young’ Variable for DID estimation Sept 1Sept 30Dec 31 CalgaryQuebec, NSBC, ON, NB, NL January February MarchYoung AprilYoung MayYoung JuneYoung JulyYoung AugustYoung SeptemberYoung OctoberYoung NovemberYoung DecemberYoung 20

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

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

23. Table 4. Difference-in-Difference Estimates of the Implications of Being “Young in Class” for Hyperactivity Symptoms. Boys + Girls BoysGirls (1)(2)(3) Young 0.486*** 0.124) 0.515*** (0.157) 0.453*** (0.089) Boy1.057*** (0.035) N241461227011876 Other covariates included: (Log of) Family Equivalent Income, Parental Education, Family Structure, Immigrant Status, Child’s Health, Cycle Dummies. Cubic age in months. 23

24. Robustness Checks 24  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. BC Quebec Ontario NS 25

26. Research Questions about Pre-school hyperactivity 26  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?

27. 27

28. 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’

29. 29 Table 5. Controlling for Pre-school Hyperactivity in Regression Discontinuity Models. 3 month window. Boys + Girls (1)(2)(3) Young 0.369* (0.195) 0.342** (0.170) 0.343** (0.170) Hyperactivity Score at 2/3 0.417*** (0.020) 0.420*** (0.029) Hyperactivity at 2/3 X Young -0.005 (0.040) Boy0.934*** (0.105) 0.784*** (0.100) 0.784*** (0.100) N9579

30. Table 6. Controlling for Pre-school Hyperactivity in Difference-in-Difference Estimates. Boys + Girls (1)(2)(3) Young 0.430** (0.141) 0.405** (0.133) 0.404** (0.133) Hyperactivity Score at 2/3 0.410*** (0.005) 0.395*** (0.025) Boy1.030*** (0.075) 0.894*** (0.073) 0.894*** (0.072) Hyperactivity at 2/3 X Young 0.028 (0.041) 30

31. 31 Table 6b. Controlling for “High” Pre-school Hyperactivity in Difference-in-Difference Estimates. Boys + Girls (1)(2) Young 0.430** (0.141) 0.293* (0.148) Hyperactivity above 75 th percentile at age 2/3 1.670*** (0.135) Boy1.030*** (0.075) 0.946*** (0.077) High Hyperactivity at 2/3 X Young 0.444*** (0.128)

32. 32 Table 6c. Controlling for Pre-school Hyperactivity in Difference-in-Difference Estimates. Boys compared to Girls. BoysGirls Young 0.483** (0.164) 0.405** (0.133) Hyperactivity Score at 2/3 0.413*** (0.027) 0.375*** (0.026) Hyperactivity at 2/3 X Young -0.016 (0.069) 0.076** (0.024) N97939508

33. Conclusions 33  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? 34  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! 35

36. Hyperactivity Score by Province 36

37. Hyperactivity More Persistent for Boys than for Girls 37

38. 38 Different Age Patterns for Boys and Girls. RD models. 6 month window. BoysGirls Young0.910*** (0.217) 0.522*** Days from Cutoff0.0027** (0.0010) 0.0006 (0.0008)

39. 39 Different Age Patterns for Boys and Girls. DD models. BoysGirls (1)(2)(4)(5) Young0.521*** (0.164) 0.524*** (0.164) 0.433*** (0.089) 0.454*** (0.090) Age in Months 0.022 (0.014) 0.033 (0.021) 0.033 (0.013) 0.115*** (0.020) Age Squared-0.0001 (0.0001) -0.0007*** (0.0001)