School Start Age and Hyperactivity in Canadian

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

Motivation 3







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)

Consequences of ADHD in Educational Context 4

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

School Start Age and Hyperactivity 5



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

Misdiagnosis not the Whole Story? 6

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

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)

Research Questions 7

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



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?

School Entering Rules in Canada 8



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

2004

from early September to March during1987-

Cut-Off Dates for School Entry Sep. 1

Sep. 30 Dec. 1

Dec. 31

Last Day of Mar. 1 Feb.

AB

QC

BC SK MB(97-04) ON NB NL

AB

Calgary NS School District

MB(8796)

AB

9

Lethbridge Red Deer Lloydminster Grande Prairie Wetaskiwin

AB

Medicine Edmonton Hat School School District District

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)

Data 11







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

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

Hyperactivity Index 13



“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 

Research Strategy I. 14



Regression Discontinuity

Hyperi = α+ τ Youngi + γ f(bdi-ci) + β1 Province i + β2 Cycle i + β3 Grade i + λ Xi + ε i 

Compare children within a province and grade who are born ‘just before’ and ‘just after’ the legal cutoff date

Illustration of RD approach 15

0

1

2

3

4

5

6

PMK Assessed Hyperactivity Score

-10

0 15-Day Blocks of Age Relative to the Cut-Off Date

10

Table 1. Regression Discontinuity Estimates of the Effect of School Starting Age on Hyperactivity Scores. 4 to 9 year olds. Sample Mean Young 4.099

3 month window N=12491

4.100

6 month window N=24878

4.095

16

(2)

(3)

(4)

0.530** 0.477** 0.573*** 0.562*** (0.231) (0.226) (0.199) (0.199)

2 month window N=8293

+ Covariates

(1)

x

(5)

(6)

0.661*** (0.150)

0.714*** (0.149)

x

x

x

x

x

x

x

x

Boys and Girls Compared 17

1

2

3

4

5

6

PMK Assessed Hyperactivity Score - Girls

0

0

1

2

3

Mean Value

4

5

6

PMK Assessed Hyperactivity Score - Boys

-10

0 15-Day Blocks of Age Relative to the Cut-Off Date

10

-10

0 15-Day Blocks of Age Relative to the Cut-Off Date

10

Table 2. Regression Discontinuity Estimates of the Effect of School Starting Age on Hyperactivity Scores. Boys vs Girls. Boys Mean Young 2 month window

4.55

3 month window

4.55

6 month window

4.62

+ Covariates N 18

Girls

(1)

(2)

(3)

0.681* (0.345)

0.935*** (0.295)

0.910*** (0.217)

x

Mean

3.64 x

(4)

(5)

(6)

0.252 (0.25)

0.173 (0.220)

0.523*** (0.178)

x

3.61

x

x

3.57

x

x

x

x

x

x

x

4133

6184

12270

4032

5955

11876

Research Strategy II. 19

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 

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Some Provincial Variation in ‘Young’ Variable for DID estimation Sept 1 Sept 30 Dec 31 Calgary Quebec, NS BC, ON, NB, NL January February March Young April Young Young May Young Young June Young Young July Young Young Young August Young Young Young September Young Young October Young November Young December Young

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

4.8 4.6 4.4 4.2

Quebec Ontario

4 3.8 3.6 3.4 Young in QC but not ON

Young in ON but not QC

DID Estimation 22

Hyperi      Young6m osip  1  Ageinm onth si 

 2  Cyclei  3  Gradei    X i   i All regressions control age in months (have done everything using higher order terms in age in months with no change in findings)

Table 4. Difference-in-Difference Estimates of the Implications of Being “Young in Class” for Hyperactivity Symptoms. Boys + Girls

Young Boy

N

Boys

Girls

(1)

(2)

(3)

0.486*** 0.124)

0.515*** (0.157)

0.453*** (0.089)

12270

11876

1.057*** (0.035) 24146

Other covariates included: (Log of) Family Equivalent Income, Parental Education, Family Structure, Immigrant Status, Child’s Health, Cycle Dummies. Cubic age in months.

23

Robustness Checks 24





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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)

Quebec

BC

.001

.0015

Density

.002

.0025

.003 .0025 .002

.0005

.001

Density

.0015 .0005

-200

-100

0 DisCutOff

100

200

-200

kernel = epanechnikov, bandwidth = 18.9343

0 DisCutOff

100

200

100

200

NS .003

Kernel density estimate

.002 .0015 .001

.0015

Density

.002

.0025

.0025

.003

Kernel density estimate

.0005

.0005

.001

Density

-100

kernel = epanechnikov, bandwidth = 15.6109

Ontario

-200

-100

0 DisCutOff

kernel = epanechnikov, bandwidth = 14.8736

25

Kernel density estimate

.003

Kernel density estimate

100

200

-200

-100

0 DisCutOff

kernel = epanechnikov, bandwidth = 19.7549

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?

0

.05

.1

.15

.2

Distribution of Pre-Kindergarten Hyperactivity Score

0

5

10 Hyperactivity Score Boy

27

Girl

15

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’ 

Table 5. Controlling for Pre-school Hyperactivity in Regression Discontinuity Models. 3 month window. Boys + Girls

Young

(1)

(2)

(3)

0.369* (0.195)

0.342** (0.170)

0.343** (0.170)

0.417*** (0.020)

0.420*** (0.029)

Hyperactivity Score at 2/3 Hyperactivity at 2/3 X Young Boy

29

N

-0.005 (0.040) 0.934*** (0.105)

0.784*** (0.100)

9579

0.784*** (0.100)

Table 6. Controlling for Pre-school Hyperactivity in Difference-in-Difference Estimates. Boys + Girls

Young

(1)

(2)

(3)

0.430** (0.141)

0.405** (0.133)

0.404** (0.133)

0.410*** (0.005)

0.395*** (0.025)

0.894*** (0.073)

0.894*** (0.072)

Hyperactivity Score at 2/3 Boy

Hyperactivity at 2/3 X Young

1.030*** (0.075)

0.028 (0.041) 30

Table 6b. Controlling for “High” Pre-school Hyperactivity in Difference-in-Difference Estimates. Boys + Girls

Young

(1)

(2)

0.430** (0.141)

0.293* (0.148) 1.670*** (0.135)

75th

Hyperactivity above percentile at age 2/3 Boy

High Hyperactivity at 2/3 X Young 31

1.030*** (0.075)

0.946*** (0.077) 0.444*** (0.128)

Table 6c. Controlling for Pre-school Hyperactivity in Difference-in-Difference Estimates. Boys compared to Girls. Boys

Girls

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)

9793

9508

N

32

Conclusions 33

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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

Policy? 34

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

Thanks! 35

Hyperactivity Score by Province Parent's Report of Child's Hyperactivity

36

5 4.5 4 3.5 3 2.5 2 1.5 1 0.5 0 NL

PEI

NS

NB

QB Old

ON Young

MB

SK

AB

BC

Hyperactivity More Persistent for Boys than for Girls 37

2.5

3

3.5

4

4.5

Age Profile of Parent Report Hyperactivity Score

6

7

8

9

10

Age in Years Boy

Girl

11

Different Age Patterns for Boys and Girls. RD models. 6 month window. Boys

Girls

Young

0.910*** (0.217)

0.522***

Days from Cutoff

0.0027** (0.0010)

0.0006 (0.0008)

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Different Age Patterns for Boys and Girls. DD models. Boys

Girls

(1)

(2)

(4)

(5)

Young

0.521*** (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

39

-0.0001 (0.0001)

-0.0007*** (0.0001)