socioeconomic determinants of body mass index of adult chinese in the 1990s

Socioeconomic Socioeconomic Determinants of Body Determinants of Body Mass Index of Adult Mass Index of Adult Chinese in the 1990sChinese in the 1990s

Zhehui Luo, Ph.D. MSZhehui Luo, Ph.D. MS

Department of EpidemiologyDepartment of Epidemiology

Michigan State UniversityMichigan State University

OutlineOutline

Simple ModelSimple Model Data and Econometric IssuesData and Econometric Issues Trends and DescriptivesTrends and Descriptives Results of Reduced Form Results of Reduced Form

DemandDemand Results of Dynamic DemandResults of Dynamic Demand Results of Production FunctionResults of Production Function

The ModelThe Model

, , ; ,0,... 0{ , , } 1,...,

T tMax U h x lt t tt T tx l mit it it i n

, , , , ;1h f h m l zi it it it it ct itit

s. t.

wT l l hit it it it

(1 )1 1 1 1 1

n n nx m wA r A p x p m w l yt t it t it it it tt t i i i

The ModelThe Model

(1 ) 11

(1 )1

mU fr p wh h it itit t txptU f f rx m mtit t

(1 )1 1

r Uht tthusU tht

txpt

The ModelThe Model

If total time available for leisure and If total time available for leisure and work is not affected by health statuswork is not affected by health status

Labor is the same as the effective Labor is the same as the effective labor in Grossman’s senselabor in Grossman’s sense

Equilibrium condition is: Equilibrium condition is:

(1 ) 11

1

mU fr ph hit t txptU f fx m mtit t

Estimating EquationsEstimating Equations

, , , , , , , , , ;, , ,t t

x h l m g p p w yx m i i cx h l m hi

, , , , , ;1 1 1 1 1x m

h f h p p w yit itit t t it t


The DataThe Data

Chinese Health and Nutrition Survey Chinese Health and Nutrition Survey (CHNS) 1989, 1991, 1993 and 1997(CHNS) 1989, 1991, 1993 and 1997

Carolina Population Center at the Carolina Population Center at the University of North Carolina, Institute University of North Carolina, Institute of Nutrition and Food Hygiene, Chinese of Nutrition and Food Hygiene, Chinese Academy of Preventive MedicineAcademy of Preventive Medicine

Sampling: multistage, random cluster Sampling: multistage, random cluster processprocess

The DataThe Data Adults aged 20 and aboveAdults aged 20 and above Excluding pregnant womenExcluding pregnant women Sample size: Sample size:

1989: 4550 persons, 2736 1989: 4550 persons, 2736 householdshouseholds

1991: 7356 persons, 3402 HH1991: 7356 persons, 3402 HH



Sample SelectionSample Selection

Study Study SampleSample OutsideOutside P-valueP-value

AgeAge 40.940.9 35.935.9 0.0000.000

% Male% Male 48.348.3 52.052.0 0.0000.000

EducatioEducationn

6.56.5 7.07.0 0.0000.000

% Urban% Urban 32.632.6 32.532.5 0.9220.922

Real Real PCINCPCINC 12101210 11931193 0.4370.437

Real Real AssetsAssets 53495349 54675467 0.5620.562

The DataThe Data BMI: Weight (kg)/ height (mBMI: Weight (kg)/ height (m22))

ClassificatioClassificationn

BMI RangeBMI Range Health RiskHealth Risk

UnderweightUnderweight <18.5<18.5 IncreasedIncreased

NormalNormal 18.5~<2518.5~<25 LeastLeast

OverweightOverweight 25~<3025~<30 IncreasedIncreased

ObeseObese

Class IClass I

Class IIClass II

Class IIIClass III

30~<3530~<35

35~<4035~<40

>=40>=40

HighHigh

Very HighVery High

HighestHighest

The DataThe Data Calorie, fat, protein intakes and percent Calorie, fat, protein intakes and percent

of Calories from fat, protein and of Calories from fat, protein and carbohydratescarbohydrates

The 1991 China Food Composition TableThe 1991 China Food Composition Table 1 gram fat = 9 Kcal energy1 gram fat = 9 Kcal energy

1 gram protein = 4 Kcal energy1 gram protein = 4 Kcal energy

1 gram carbohydrates=4 Kcal energy1 gram carbohydrates=4 Kcal energy

Economic Development in Economic Development in 1989 ~ 19971989 ~ 1997

19891989 19911991 19931993 19971997

Real PC IncomeReal PC Income 677677 659659 823823 10391039

Prod AssetsProd Assets 243243 266266 425425 636636

Years of Years of EducationEducation 7.327.32 6.016.01 6.046.04 6.586.58

% Employed% Employed 9696 8282 8080 7777

% HH water % HH water factoryfactory 3434 4141 4242 4949

Mean BMI, Mean BMI, WomenWomen 21.721.7 22.122.1 22.122.1 22.622.6

Mean BMI, MenMean BMI, Men 21.221.2 21.621.6 21.921.9 22.322.3

Trends in Food Trends in Food AvailabilityAvailability

Source: FAO 2002 Food Balance Sheet for China

Trends in overweight and Trends in overweight and obesityobesity

% Men and Women % Men and Women overweight (BMI overweight (BMI 25)25)

0

5

10

15

20

25

1989 1991 1993 1997

Men Women

% Men and Women% Men and Women

obese (BMI 30)obese (BMI 30)

0

0.5

1

1.5

2

2.5

3

1989 1991 1993 1997

Men Women

Trends in overweightTrends in overweight

% Men overweight % Men overweight by age groupsby age groups

% Women % Women overweight by age overweight by age groupsgroups

0

5

10

15

20

25

1989 1991 1993 1997

Age 20-39 Age 40-59 Age 60+

0

5

10

15

20

25

30

1989 1991 1993 1997

Age 20-39 Age 40-59 Age 60+


% Men overweight % Men overweight by rural-urban by rural-urban residenceresidence

% Women % Women overweight by overweight by rural-urban rural-urban residenceresidence

0

5

10

15

20

25

30

1989 1991 1993 1997

Urban Rural

0

5

10

15

20

25

30

1989 1991 1993 1997

Urban Rural


% Men overweight % Men overweight by education levelsby education levels

% Women % Women overweight by overweight by education levelseducation levels

0

5

10

15

20

25

30

1989 1991 1993 19970

5

10

15

20

25

1989 1991 1993 1997

No EduSome PrimaryPrimaryMiddle SchoolHigh SchoolCollege

BMI Distribution: MenBMI Distribution: Men

Russel Davidson and Jean-Yves Duclos (2000), performed with DAD 4.3

BMI Distribution: BMI Distribution: WomenWomen

Russel Davidson and Jean-Yves Duclos (2000), performed with DAD 4.3

Estimating EquationEstimating Equation

The linear representation:The linear representation:

Baltagi and Wu (1999)Baltagi and Wu (1999)

2~ (0, )

2 2~ (0, ) , ~ (0, )1

1,...,

1,...,

,

h X uit it it

where u IID uit i it i

IID or IIDe vit it it itit

i n

t Ti

Estimating EquationEstimating Equation

Econometric IssuesEconometric Issues Measurement ErrorsMeasurement Errors Functional form: nonlinearity of effectsFunctional form: nonlinearity of effects Age, cohort and period effectsAge, cohort and period effects

Age, Period and Cohort Age, Period and Cohort AnalysisAnalysis

To identify: To identify: Origin-related process – cohort effect Origin-related process – cohort effect

dominantdominant Aging processAging process Instantaneous process – function of timeInstantaneous process – function of time

Linear dependency: Linear dependency: Deaton (1997), Holford (1983)Deaton (1997), Holford (1983)

, , , , , ,y ui c a t c a t i c a t

0, 0, 01 1 1 1 1 1

P A Tor c a tc a t

(3.1)


Spacing of the data determines the Spacing of the data determines the number of extra constraints (n) number of extra constraints (n) neededneeded

CHNS 1989, 1991, 1993, 1997: n=2CHNS 1989, 1991, 1993, 1997: n=2 If arbitrarily impose two constraints:If arbitrarily impose two constraints:With Perfect Coliearity

age

Male age effect Female age effect

21 75-3.31

3.07

With Perfect Colinearity

cohort

Male cohort effect Female cohort effect

1906 1960-5.71

8.44


Meaningful constraints:Meaningful constraints:

Source: State Statistical Bureau (1992): 1990 Population Census of China.


Results from age dummies, five-year Results from age dummies, five-year cohort dummies and year dummies:cohort dummies and year dummies:

Ma

le/F

em

ale

Ag

e E

ffect

sId

en

tifie

d w

ith F

ive

-ye

ar

coh

ort

s

age

Male Age Effect Fmale Age Effect

20 25 30 35 40 45 50 55 60 65 70 75

-1.60

-1.20

-0.80

-0.40

0.00

0.40

0.80

1.20

1.60

2.00

2.40

Reduced Form Demand Reduced Form Demand (I)(I)

Male Female

BMI Calories % Fat % Protein


Some primary 0.02 2.07 0.50 0.14 0.22 14.19 0.33 0.17

Primary 0.04 -1.25 0.89 0.19 0.47 1.80 1.22 0.45

Middle School 0.05 -42.83 1.78 0.37 0.01 -52.28 1.93 0.58

High School 0.21 -66.05 2.07 0.48 -0.32 -76.89 2.70 0.79

College 0.10 -57.37 2.36 0.79 -0.63 -42.83 3.02 1.23

Prod Assets spline 1

0.02 23.10 0.12 0.03 0.05 2.86 0.03 0.03


0.04 -13.19 0.04 0.04 -0.02 3.33 0.16 0.05

P-value

Education 0.7229 0.2040 0.0000 0.0007 0.0000 0.0315 0.0000 0.0000

Prod Assets 0.0011 0.0003 0.0111 0.0003 0.0877 0.2064 0.0002 0.0000


Male Age 20-39 Female Age 20-39



Some primary -0.04 53.69 1.81 0.13 -0.02 -25.47 0.17 0.17

Primary -0.11 31.18 2.09 -0.01 0.11 9.76 1.14 0.37

Middle School -0.10 -32.03 2.90 0.31 -0.31 -53.46 2.14 0.61

High School 0.14 -55.27 3.36 0.33 -0.71 -63.97 2.69 0.80

College 0.02 -60.00 4.39 1.00 -0.98 -80.17 3.03 1.21


-0.002 31.13 0.24 0.07 0.04 3.81 0.04 0.01


0.06 -16.49 -0.03 0.03 -0.05 2.59 0.18 0.06

P-value

Education 0.5085 0.1118 0.0001 0.0046 0.0008 0.1431 0.0000 0.0000

Prod Assets 0.0052 0.0007 0.0043 0.0003 0.3412 0.2753 0.0048 0.0108


Male Age 40-59 Female Age 40-59



Some primary -0.02 -59.65 0.95 -0.21 0.33 -31.10 0.29 0.08

Primary -0.13 -41.88 1.17 -0.03 0.48 -39.53 0.57 0.44

Middle School -0.03 -83.21 2.33 0.03 0.21 -96.89 0.95 0.50

High School 0.02 -50.87 1.90 0.86 0.59 6.90 3.40 0.67

College 0.16 -73.47 0.97 0.14 0.05 35.74 3.29 0.83


-0.01 23.00 0.19 0.02 0.02 5.01 -0.04 0.03


0.06 -19.65 0.14 0.05 0.07 6.63 0.26 0.08

P-value

Education 0.9266 0.8450 0.0442 0.0446 0.2724 0.2389 0.0808 0.0533

Prod Assets 0.0391 0.1095 0.0064 0.0740 0.0209 0.2684 0.0284 0.0028


Male Age 60+ Female Age 60+



Some primary -0.30 -2.12 -0.44 0.46 -0.02 -89.88 -0.68 0.29

Primary -0.18 -44.81 0.40 0.81 -0.37 -33.01 3.49 0.74

Middle School -0.39 -44.15 0.26 1.08 -0.31 195.74 3.26 0.28

High School 0.04 8.32 1.42 1.38 0.92 897.42 13.86 -0.40

College -0.55 115.59 2.51 1.70 0.60 271.00 6.27 -0.12


0.08 -6.55 -0.25 -0.08 0.10 3.59 0.01 0.12


-0.06 29.99 -0.03 0.05 -0.03 -4.03 0.03 -0.05

P-value

Education 0.8478 0.8510 0.5739 0.0550 0.8362 0.0184 0.0000 0.8506

Prod Assets 0.6805 0.0762 0.3696 0.5752 0.2370 0.9166 0.9695 0.2812


Urban Male Urban Female



Some primary -0.03 -2.73 0.11 0.14 -0.05 -7.24 -0.08 0.28

Primary -0.15 34.63 1.28 0.73 0.02 -38.34 1.15 0.53

Middle School -0.14 -58.16 1.34 0.75 0.08 -71.63 2.04 0.676

High School 0.30 -38.71 2.06 0.86 -0.29 -63.39 2.76 1.03

College -0.02 -55.81 1.71 1.26 -0.39 -10.82 3.11 1.39


0.03 11.03 -0.06 0.01 -0.00 2.05 0.04 0.01


0.01 0.55 0.10 0.00 -0.02 3.59 0.20 0.04

P-value

Education 0.3256 0.3963 0.0720 0.0002 0.3342 0.4694 0.0013 0.0001

Prod Assets 0.4605 0.3083 0.6197 0.9556 0.7514 0.7298 0.0154 0.2191


Rural Male Rural Female



Some primary -0.08 -7.72 0.64 0.09 0.16 -25.47 0.38 0.13

Primary -0.09 -23.46 0.78 -0.03 0.44 9.76 1.18 0.41

Middle School -0.07 -41.87 1.93 0.23 -0.12 -53.46 1.83 0.56

High School -0.00 -96.45 2.08 0.33 -0.31 -63.97 2.87 0.62

College 0.14 -31.53 3.61 0.43 -0.83 -80.17 3.32 1.05


0.01 30.56 0.23 0.03 0.07 3.81 0.04 0.03


0.05 -20.89 -0.04 0.06 -0.03 2.59 0.14 0.05

P-value

Education 0.9442 0.3826 0.0000 0.0906 0.0013 0.1431 0.0000 0.0003

Prod Assets 0.0018 0.0002 0.0020 0.0000 0.0222 0.2753 0.0076 0.0002

Probability Model for Probability Model for OverweightOverweight

Male Female

Rural 20-39 40-59 60+ Rural 20-39 40-59 60+

Some primary -0.0004 0.001 -0.024 -0.022 0.002 -0.016 0.01 -0.013

Primary -0.009 -0.012 -0.024 -0.015 0.025 -0.016 0.029 -0.099

Middle School 0.006 -0.007 -0.015 -0.084 -0.008 -0.029 0.0060 -0.11

High School 0.022 0.014 0.006 -0.014 -0.01 -0.064 0.099 0.177

College -0.005 -0.011 0.008 -0.133 -0.09 -0.074 0.007 0.047


-0.002 -0.001 -0.003 0.008 0.001 0 0 0.015


0.005 0.006 0.010 -0.014 0.001 -0.002 0.008 -0.015

P-value

Education 0.4059 0.5130 0.7246 0.3056 0.0423 0.0272 0.3465 0.2562

Prod Assets 0.0416 0.0221 0.0115 0.2615 0.5516 0.6709 0.0499 0.1341


Results from the basic model:Results from the basic model: Education effect on female BMI inversely U-shapedEducation effect on female BMI inversely U-shaped % Calories from fat and protein increase with % Calories from fat and protein increase with

educationeducation Male BMI increases with productive assets, female Male BMI increases with productive assets, female

inversely U-shapedinversely U-shaped % Calories from fat and protein increase with % Calories from fat and protein increase with

assets, except for urban men – U-shapedassets, except for urban men – U-shaped

Reduced Form Demand Reduced Form Demand (II)(II)

Male Female

BMI Log Calories

Log Fat

Log Protein

BMI Log Calories

Log Fat

Log Protein

Price of rice 0.06 -0.07 -0.16 -0.10 -0.01 -0.03 -0.11 -0.08

Price of eggs -0.01 -0.02 -0.03 -0.03 -0.01 -0.01 -0.03 -0.02

Price of pork -0.01 0.02 0.26 0.08 -0.06 0.02 0.31 0.08

Water factory 0.73 -0.03 0.17 0.01 0.17 0.02 0.17 0.04

Inhouse no flush -1.35 0.22 0.35 0.19 -0.94 0.25 0.55 0.24

Much Excreta -0.04 -0.00 0.37 -0.08 0.38 -0.21 0.08 -0.09

P-value

Prices 0.8017 0.0000 0.0000 0.0000 0.4425 0.0000 0.0000 0.0000

Water sources 0.0000 0.0088 0.0052 0.0220 0.6968 0.0064 0.0001 0.0111

Toilet types 0.0687 0.0225 0.6854 0.5398 0.2697 0.0000 0.0082 0.0049

Excreta 0.3723 0.0000 0.0001 0.0003 0.4206 0.0177 0.0345 0.1375

Reduced Form Demand Reduced Form Demand (II)(II)

Results from the augmented model:Results from the augmented model: Prices significant without controlling Prices significant without controlling

community dummies in BMI regressionscommunity dummies in BMI regressions Negative price elasticity of rice, eggs for Negative price elasticity of rice, eggs for

calories, fat and protein; positive price calories, fat and protein; positive price elasticity of porkelasticity of pork

Better water source – fat, protein intakes and Better water source – fat, protein intakes and male BMI: positivemale BMI: positive

More excreta – calories and protein: negativeMore excreta – calories and protein: negative

Dynamic BMI DemandDynamic BMI Demand

Estimating Equation:Estimating Equation:

Instruments: previous years HH Instruments: previous years HH resources, community characteristicsresources, community characteristics

Results:Results: In short terms lagged BMI is good In short terms lagged BMI is good

summary measure of health statussummary measure of health status Age effect for women still strong, aging Age effect for women still strong, aging

factorfactor

, , , , , ;1 1 1 1 1x m

h f h p p w yit itit t t it t

Dynamic BMI DemandDynamic BMI Demand

Male Female

BMI 93 BMI 97 BMI 93 BMI 97

OLS IV OLS IV OLS IV OLS IV

Lagged BMI 0.57** 0.84** 0.39** 0.44** 0.55** 0.64** 0.48** 0.40**

Some primary -0.10 -0.09 -0.48* -0.49* 0.19 0.16 0.20 0.24

Primary -0.23 -0.20 0.13 0.13 0.28 0.22 0.05 0.08

Middle School -0.25 -0.27 0.29 0.30 0.05 0.04 0.00 -0.00

High School -0.08 -0.16 0.21 0.20 -0.31 -0.31 -0.34 -0.38

College 0.06 0.07 0.51 0.50 0.34 0.43 -1.02 -1.05*

P-value

Lagged BMI=1 0.0000 0.3946 0.0000 0.0001 0.0000 0.0007 0.0000 0.0001

Hausman 0.0747 0.6242 0.4052 0.5769

Overidentification 0.4555 0.1911 0.9534 0.8015

BMI Production FunctionBMI Production Function

Estimating equation:Estimating equation:

Instruments: previous years HH Instruments: previous years HH resources, community characteristicsresources, community characteristics

Results:Results: In a short period, BMI – a random walk In a short period, BMI – a random walk

processprocess Heavy physical activities negative in OLS Heavy physical activities negative in OLS

and positive in IVand positive in IV Food intakes not significantFood intakes not significant


BMI Production FunctionBMI Production Function

Male Log BMI 93 Female Log BMI 93

IV OLS IV OLS

Log BMI 91 1.002 0.707** 0.901** 0.673**

Moderate to heave PA

0.009** -0.011** 0.008 -0.016

Calories 0.002 -0.002** -0.010 0.001

Fat -0.001 0.000 -0.001 0.000

Protein -0.001 0.001** 0.002 0.000

Lagged BMI=1 0.9871 0.0000 0.2782 0.0000

Hausman 3.08

(0.0031) 5.81

(0.0000)

Overidentification 10.61

(0.9364) 26.61

(0.1141)

Limitations and Future Limitations and Future researchresearch

Measurement: productive assets, fat Measurement: productive assets, fat intakeintake

UncertaintyUncertainty AttritionAttrition Health and Labor Market Health and Labor Market

ParticipationParticipation Intra-household allocation and HealthIntra-household allocation and Health

socioeconomic determinants of body mass index of adult chinese in the 1990s

Documents

women overweight bmi

cohort dummies

age dummies

cohort analysisto

cohort analysisresults

cohort analysisspacing

period effectsage

age groupstrends