Height and Cognitive Achievement among Indian Children

NCAER – 28 September 2011Dean Spears

Height & cognitive achievement

• There are life-long health and economic consequences of early-life health and net nutrition (eg Currie 2009)

• Height is determined by genetic potential and net nutrition (eg Deaton 2007; Fogel)– “the difference between food intake and the

losses to disease”• “Height is positively related to cognitive

ability, which is rewarded in the labor market” (Case & Paxson 2008)

on average

Case & Paxson, Demography, 2010

Why do we care? Why look in India?

• Further demonstrates deep importance of childhood health environments

• Effects could be different where the average child is very deprived

• Contributes to debates on malnutrition in India

• Recent literature, especially with big data sets, has focused on rich countries

The India Human Development Survey

• … needs no introduction here!

Thank you for such a wonderful data set!

IHDS cognitive achievement tests

• Reading (5 levels)– none, letters, words, paragraphs, stories

• Math (4 levels)– none, numbers, subtraction, division

• Writing (2 levels)– none, writes with 2 or fewer mistakes

The Indian gradientPart One

.2.4

.6.8

1

-4 -3 -2 -1 0 1height-for-age z-score

letters wordsparagraphs stories

.6.7

.8.9

1re

ads

wor

ds

-4 -3 -2 -1 0 1height for age z-score

rural, male rural, femaleurban, male urban, female

.5.6

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-4 -3 -2 -1 0 1height for age z-score

8 910 11

.3.4

.5.6

.7.8

read

s pa

ragr

aphs

-4 -3 -2 -1 0 1height for age z-score

8 910 11

ordered logitsby age, by urban-rural

achievementi = 0 + 1 hfai + i +

step 2: 2 malei + 3 Engi + 3 Hindii + θ Gi +

step 3: 4 CPCi + 5 CPCi² + 5 hh sizei + 6 childreni + 5 edi

adult + 5 ediwoman.

ordered logitsby age, by urban-rural

achievementi = 0 + 1 hfai + i +

step 2: 2 malei + 3 Engi + 3 Hindii + θ Gi +

step 3: 4 CPCi + 5 CPCi² + 5 hh sizei + 6 childreni + 5 edi

adult + 5 ediwoman.

ordered logitsby age, by urban-rural

achievementi = 0 + 1 hfai + i +

step 2: 2 malei + 3 Engi + 3 Hindii + θ Gi +

step 3: 4 CPCi + 5 CPCi² + 5 hh sizei + 6 childreni + 5 edi

adult + 5 ediwoman.

urban rural no controls categories household no controls categories household

Reading nage 8 0.321*** 0.329*** 0.293*** 0.368*** 0.369*** 0.338*** urban: 792

(0.0566) (0.0595) (0.0586) (0.0514) (0.0524) (0.0545) rural: 1847age 9 0.297*** 0.276*** 0.237*** 0.361*** 0.350*** 0.294*** urban: 760

(0.0579) (0.0632) (0.0653) (0.0459) (0.0474) (0.0503) rural: 1607age 10 0.288*** 0.320*** 0.285*** 0.317*** 0.286*** 0.249*** urban: 1025

(0.0509) (0.0533) (0.0557) (0.0474) (0.0462) (0.0491) rural: 2468age 11 0.160* 0.145+ 0.0951 0.258*** 0.276*** 0.255*** urban: 552

(0.0816) (0.0839) (0.0914) (0.0603) (0.0589) (0.0594) rural: 1494Math age 8 0.267*** 0.239*** 0.194** 0.321*** 0.315*** 0.278*** urban: 789

(0.0638) (0.0651) (0.0664) (0.0549) (0.0579) (0.0595) rural: 1842age 9 0.384*** 0.352*** 0.307*** 0.327*** 0.313*** 0.261*** urban: 758

(0.0612) (0.0632) (0.0671) (0.0479) (0.0480) (0.0494) rural: 1604age 10 0.299*** 0.343*** 0.322*** 0.242*** 0.197*** 0.163*** urban: 1019

(0.0585) (0.0598) (0.0603) (0.0491) (0.0483) (0.0493) rural: 2464age 11 0.339*** 0.311*** 0.300*** 0.186** 0.187** 0.152** urban: 546

(0.0765) (0.0820) (0.0864) (0.0598) (0.0606) (0.0587) rural: 1483Writing age 8 0.295*** 0.318*** 0.302*** 0.321*** 0.318*** 0.302*** urban: 784

(0.0660) (0.0720) (0.0739) (0.0541) (0.0558) (0.0567) rural: 1826age 9 0.339*** 0.323*** 0.277** 0.278*** 0.250*** 0.174** urban: 757

(0.0812) (0.0836) (0.0868) (0.0667) (0.0669) (0.0675) rural: 1598age 10 0.264*** 0.321*** 0.307*** 0.270*** 0.224*** 0.180** urban: 1018

(0.0710) (0.0763) (0.0793) (0.0631) (0.0611) (0.0635) rural: 2450age 11 0.166 0.137 0.0892 0.174* 0.187* 0.157* urban: 544 (0.110) (0.117) (0.126) (0.0724) (0.0748) (0.0752) rural: 1478

urban rural no controls categories household no controls categories household

Reading nage 8 0.321*** 0.329*** 0.293*** 0.368*** 0.369*** 0.338*** urban: 792

(0.0566) (0.0595) (0.0586) (0.0514) (0.0524) (0.0545) rural: 1847age 9 0.297*** 0.276*** 0.237*** 0.361*** 0.350*** 0.294*** urban: 760

(0.0579) (0.0632) (0.0653) (0.0459) (0.0474) (0.0503) rural: 1607age 10 0.288*** 0.320*** 0.285*** 0.317*** 0.286*** 0.249*** urban: 1025

(0.0509) (0.0533) (0.0557) (0.0474) (0.0462) (0.0491) rural: 2468age 11 0.160* 0.145+ 0.0951 0.258*** 0.276*** 0.255*** urban: 552

(0.0816) (0.0839) (0.0914) (0.0603) (0.0589) (0.0594) rural: 1494Math age 8 0.267*** 0.239*** 0.194** 0.321*** 0.315*** 0.278*** urban: 789

(0.0638) (0.0651) (0.0664) (0.0549) (0.0579) (0.0595) rural: 1842age 9 0.384*** 0.352*** 0.307*** 0.327*** 0.313*** 0.261*** urban: 758

(0.0612) (0.0632) (0.0671) (0.0479) (0.0480) (0.0494) rural: 1604age 10 0.299*** 0.343*** 0.322*** 0.242*** 0.197*** 0.163*** urban: 1019

(0.0585) (0.0598) (0.0603) (0.0491) (0.0483) (0.0493) rural: 2464age 11 0.339*** 0.311*** 0.300*** 0.186** 0.187** 0.152** urban: 546

(0.0765) (0.0820) (0.0864) (0.0598) (0.0606) (0.0587) rural: 1483Writing age 8 0.295*** 0.318*** 0.302*** 0.321*** 0.318*** 0.302*** urban: 784

(0.0660) (0.0720) (0.0739) (0.0541) (0.0558) (0.0567) rural: 1826age 9 0.339*** 0.323*** 0.277** 0.278*** 0.250*** 0.174** urban: 757

(0.0812) (0.0836) (0.0868) (0.0667) (0.0669) (0.0675) rural: 1598age 10 0.264*** 0.321*** 0.307*** 0.270*** 0.224*** 0.180** urban: 1018

(0.0710) (0.0763) (0.0793) (0.0631) (0.0611) (0.0635) rural: 2450age 11 0.166 0.137 0.0892 0.174* 0.187* 0.157* urban: 544 (0.110) (0.117) (0.126) (0.0724) (0.0748) (0.0752) rural: 1478

urban rural no controls categories household no controls categories household

Reading nage 8 0.321*** 0.329*** 0.293*** 0.368*** 0.369*** 0.338*** urban: 792

(0.0566) (0.0595) (0.0586) (0.0514) (0.0524) (0.0545) rural: 1847age 9 0.297*** 0.276*** 0.237*** 0.361*** 0.350*** 0.294*** urban: 760

(0.0579) (0.0632) (0.0653) (0.0459) (0.0474) (0.0503) rural: 1607age 10 0.288*** 0.320*** 0.285*** 0.317*** 0.286*** 0.249*** urban: 1025

(0.0509) (0.0533) (0.0557) (0.0474) (0.0462) (0.0491) rural: 2468age 11 0.160* 0.145+ 0.0951 0.258*** 0.276*** 0.255*** urban: 552

(0.0816) (0.0839) (0.0914) (0.0603) (0.0589) (0.0594) rural: 1494Math age 8 0.267*** 0.239*** 0.194** 0.321*** 0.315*** 0.278*** urban: 789

(0.0638) (0.0651) (0.0664) (0.0549) (0.0579) (0.0595) rural: 1842age 9 0.384*** 0.352*** 0.307*** 0.327*** 0.313*** 0.261*** urban: 758

(0.0612) (0.0632) (0.0671) (0.0479) (0.0480) (0.0494) rural: 1604age 10 0.299*** 0.343*** 0.322*** 0.242*** 0.197*** 0.163*** urban: 1019

(0.0585) (0.0598) (0.0603) (0.0491) (0.0483) (0.0493) rural: 2464age 11 0.339*** 0.311*** 0.300*** 0.186** 0.187** 0.152** urban: 546

(0.0765) (0.0820) (0.0864) (0.0598) (0.0606) (0.0587) rural: 1483Writing age 8 0.295*** 0.318*** 0.302*** 0.321*** 0.318*** 0.302*** urban: 784

(0.0660) (0.0720) (0.0739) (0.0541) (0.0558) (0.0567) rural: 1826age 9 0.339*** 0.323*** 0.277** 0.278*** 0.250*** 0.174** urban: 757

(0.0812) (0.0836) (0.0868) (0.0667) (0.0669) (0.0675) rural: 1598age 10 0.264*** 0.321*** 0.307*** 0.270*** 0.224*** 0.180** urban: 1018

(0.0710) (0.0763) (0.0793) (0.0631) (0.0611) (0.0635) rural: 2450age 11 0.166 0.137 0.0892 0.174* 0.187* 0.157* urban: 544 (0.110) (0.117) (0.126) (0.0724) (0.0748) (0.0752) rural: 1478

urban rural no controls categories household no controls categories household

Reading nage 8 0.321*** 0.329*** 0.293*** 0.368*** 0.369*** 0.338*** urban: 792

(0.0566) (0.0595) (0.0586) (0.0514) (0.0524) (0.0545) rural: 1847age 9 0.297*** 0.276*** 0.237*** 0.361*** 0.350*** 0.294*** urban: 760

(0.0579) (0.0632) (0.0653) (0.0459) (0.0474) (0.0503) rural: 1607age 10 0.288*** 0.320*** 0.285*** 0.317*** 0.286*** 0.249*** urban: 1025

(0.0509) (0.0533) (0.0557) (0.0474) (0.0462) (0.0491) rural: 2468age 11 0.160* 0.145+ 0.0951 0.258*** 0.276*** 0.255*** urban: 552

(0.0816) (0.0839) (0.0914) (0.0603) (0.0589) (0.0594) rural: 1494Math age 8 0.267*** 0.239*** 0.194** 0.321*** 0.315*** 0.278*** urban: 789

(0.0638) (0.0651) (0.0664) (0.0549) (0.0579) (0.0595) rural: 1842age 9 0.384*** 0.352*** 0.307*** 0.327*** 0.313*** 0.261*** urban: 758

(0.0612) (0.0632) (0.0671) (0.0479) (0.0480) (0.0494) rural: 1604age 10 0.299*** 0.343*** 0.322*** 0.242*** 0.197*** 0.163*** urban: 1019

(0.0585) (0.0598) (0.0603) (0.0491) (0.0483) (0.0493) rural: 2464age 11 0.339*** 0.311*** 0.300*** 0.186** 0.187** 0.152** urban: 546

(0.0765) (0.0820) (0.0864) (0.0598) (0.0606) (0.0587) rural: 1483Writing age 8 0.295*** 0.318*** 0.302*** 0.321*** 0.318*** 0.302*** urban: 784

(0.0660) (0.0720) (0.0739) (0.0541) (0.0558) (0.0567) rural: 1826age 9 0.339*** 0.323*** 0.277** 0.278*** 0.250*** 0.174** urban: 757

(0.0812) (0.0836) (0.0868) (0.0667) (0.0669) (0.0675) rural: 1598age 10 0.264*** 0.321*** 0.307*** 0.270*** 0.224*** 0.180** urban: 1018

(0.0710) (0.0763) (0.0793) (0.0631) (0.0611) (0.0635) rural: 2450age 11 0.166 0.137 0.0892 0.174* 0.187* 0.157* urban: 544 (0.110) (0.117) (0.126) (0.0724) (0.0748) (0.0752) rural: 1478

As linear as it seems?

Box-Cox transformation

(zλ-1)/ λ as the dependent variable

Maximizes likelihood at

λ* =1.26

Cannot reject null hypothesis that

λ =1

INDIA & THE U.S.Part Two

0.1

.2.3

.4de

nsity

-10 -5 0 5height for age z-score

U.S. (NLSY 79) India (IHDS)

cognitive achievement data

India: IHDS• reads letters• reads words• reads paragraphs• reads stories

U.S.: NLSY 79• Peabody Individual

Achievement Tests– PIAT Recognition (1-84)– PIAT Comprehension (1-84)

• Can construct comparable variables– reads letters: recognition 18– reads words: recognition 23Only reading can

be matched, unfortunately

.85

.9.9

51

read

s le

tter

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-4 -2 0 2 4height for age z-score

India US

.6.7

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India 8 9 US 8 9India 10 11 US 10 11

Famous papers have called this positive slope a

big deal!

slope in India > slope in U.S.?

achievementi = 0 + 1 hfai Indiai +

2 hfai + 3 Indiai +

4 femalei + 5 femaleiIndiai + i.

• Estimate separately for 8, 9, 10, 11 year olds• Indicate achievement with best content matches

– Reads words– Reads letters

slope in India > slope in U.S.? reads words reads letters

(1) (2) (3) (4) (5) (6) (7) (8) age 8 age 9 age 10 age 11 age 8 age 9 age 10 age 11hfa ´ India 0.0339*** 0.0373*** 0.0224*** 0.0180** 0.0253*** 0.0203*** 0.00887* 0.00816*

(0.00751) (0.00630) (0.00511) (0.00589) (0.00497) (0.00399) (0.00345) (0.00370)hfa 0.0101* 0.00716* 0.00140 0.00256 0.00168 0.00215 0.00270 -0.000647

(0.00443) (0.00287) (0.00241) (0.00162) (0.00164) (0.00112) (0.00138) (0.000414)India -0.113*** -0.0796*** -0.0900*** -0.0566*** -0.0706*** -0.0235* -0.0396*** -0.0272**

(0.0178) (0.0157) (0.0126) (0.0143) (0.0121) (0.00924) (0.00824) (0.00909)female 0.0638*** 0.0361*** 0.0219*** 0.0150*** 0.00952** 0.00487 -0.000507 0.00188

(0.00923) (0.00634) (0.00479) (0.00384) (0.00308) (0.00253) (0.00218) (0.00166)

female -0.0993*** -0.0308 -0.0625*** -0.0599*** -0.0365** -0.0225 -0.0178 -0.0220* ´ India (0.0200) (0.0177) (0.0138) (0.0158) (0.0138) (0.0115) (0.00915) (0.0102)c 0.884*** 0.944*** 0.969*** 0.979*** 0.986*** 0.991*** 0.995*** 0.997***

(0.00793) (0.00569) (0.00434) (0.00365) (0.00284) (0.00229) (0.00180) (0.00133)

R2 0.12 0.10 0.08 0.08 0.09 0.05 0.04 0.03n 6160 5827 6997 5316 6160 5827 6997 5316

Maybe I chose badly?

84 regressions, for 84 levels s

0.0%0.1%

0.1%0.1%

0.1%0.1%

0.2%0.2%

0.3%0.9%

1.7%3.8%

6.5%9.2%

11.8%14.9%

18.2%21.9%

26.2%31.1%

36.8%42.6%

49.0%54.6%

60.6%65.4%

70.3%75.1%

79.5%83.5%

86.9%89.7%

91.7%93.2%

94.3%95.5%

96.5%97.4%

98.1%98.8%

99.4%99.8%

0

0.01

0.02

0.03

0.04

0.05

0.06

reads words vs. PIAT recognition

reads paragraphs, reads stories vs. PIAT comprehension

0.1%0.1%

0.2%0.2%

0.2%0.3%

1.3%4.8%

8.5%13.8%

20.7%25.9%

31.7%39.0%

49.7%60.9%

72.7%82.7%

88.8%92.5%

94.9%96.6%

98.1%99.0%

99.5%99.7%

99.9%

100.0%

-0.00999999999999997

3.12250225675825E-17

0.01

0.02

0.03

0.04

0.05

0.06

Why the difference?

• Cognitive and height outcomes (c and z) depend on a genetic potential g, and a deduction due to early life health h and net nutrition.

• Assume gs are uncorrelated with one another and with h.

Why the difference?

• Let f be linear in both cases.

• If conditional expectations are indeed linear, εs will be uncorrelated with h.

• Further assume they are uncorrelated with one another.

Why the difference?

Why the difference?

\

•India’s slope is still greater if we regress height on cognitive achievement•The regression estimated only with the Indian data has a greater R2 than just for the U.S. data

EXPLAINING THE INDIAN GRADIENTPart 3: What is the omitted variable?

Human Development Profile of India

NCAER provided matchable data from 1994.

HDPI includes only then-rural households.

2005

11 year olds

10 year olds

9 year olds

8 year olds

1994

stepwise addition of variablesbasic 04-05 controls 93-94 wealth 93-94 food 93-94 air 93-94 waterHFA Consumption³ Income² (Grains/n)² kgs Clean fuel Defecate wash max

9 yo Income HH size² Fruits & veg /n Mod stove Defecate wash avg

10 yo Male Asset indicies Vegetarian Kitchen Defecate soap max

11 yo Ever school Housing Electricity Defecate soap avg

Gov’t school HH education Chimney Eating wash max

Son/daughter HH occupation Eating wash avg

English Eating soap max

Hindi Eating soap avg

HH education Adequate water

HH structure Water at home

Groups FEs Water very far

State FEs Toilet

Knows ORS

Table 4

p r e tt y fl a t

Sanitation variables matter

• None of the food or respiratory environment variables are individually significant

• Toilet in household: 9 pp more likely to write (t = 2.93)

• Long walk to water source: 8 pp less likely to write (t = 2.15)

• No adult washes hands before eating– True of 19 percent of children– 41 pp less likely to write (t = 2.09)

What have we learned?

• Indian slope ranges from 2.4 times to 25 times the U.S. slope.– Height is a powerful predictor of children’s cognitive

achievement– Being a short is not innocuous among Indian children

• Being one standard deviation taller is associated with being 5 percentage points more likely to be able to write, a slope that falls to only 3.4 percentage points with many controls– Much remains to understand– Sanitation, water, and hygiene seem important