Misreporting Month of Birth: Diagnosis and Implications for Research on Nutrition and Early Childhood in Developing Countries

Tufts University, Department of Economics Working Paper

54 Pages Posted: 30 Jan 2017 Last revised: 17 Jul 2018

See all articles by Anna Larsen

Anna Larsen

University of Copenhagen - Department of Economics

Derek Headey

International Food Policy Research Institute (IFPRI)

William A. Masters

Tufts University - Friedman School of Nutrition Science and Policy; Tufts University - Department of Economics

Multiple version iconThere are 2 versions of this paper

Date Written: July 3, 2018

Abstract

A large literature uses children's birthdays to identify exposure to shocks and estimate their impacts on later outcomes. Using height-for-age Z scores (HAZ) for over 990,000 children in 62 countries from 163 Demographic and Health Surveys (DHS), we show how random errors in birthdates create artifacts in HAZ that can be used to diagnose the extent of age misreporting. The most important artifact is an upward gradient in HAZ by recorded month of birth (MOB) from start to end of calendar years, resulting in a large HAZ differential between December- and January-born children of -0.32 HAZ points. We observe a second artifact associated with round ages, with a downward gradient in HAZ by recorded age in months, then an upward step after reaching ages 2, 3 and 4. These artifacts have previously been interpreted as actual health shocks. We show that they are not related to agro-climatic conditions, but are linked to the type of calendar used and arise mainly when enumerators do not see the child's birth registration cards. We explain the size of the December-January gap through simulation where 11% of children have their birthdate replaced by a random month. We find a minor impact on the average stunting rate, but a larger impact in specific error-prone surveys. We further show how misreporting MOB causes attenuation bias when MOB is used for identification of shock exposure, and also systematic bias in the impact on HAZ of events that occur early or late in each calendar year.

Keywords: nutrition, height-for-age, stunting, measurement error, child age

JEL Classification: I15; J13; C81; C83

Suggested Citation

Larsen, Anna and Headey, Derek and Masters, William A., Misreporting Month of Birth: Diagnosis and Implications for Research on Nutrition and Early Childhood in Developing Countries (July 3, 2018). Tufts University, Department of Economics Working Paper. Available at SSRN: https://ssrn.com/abstract=2907726 or http://dx.doi.org/10.2139/ssrn.2907726

Anna Larsen

University of Copenhagen - Department of Economics ( email )

Ă˜ster Farimagsgade 5
Bygning 26
1353 Copenhagen K.
Denmark

Derek Headey

International Food Policy Research Institute (IFPRI) ( email )

1201 Eye St, NW,
Washington, DC 20005
United States

William A. Masters (Contact Author)

Tufts University - Friedman School of Nutrition Science and Policy ( email )

150 Harrison Avenue
Boston, MA 02111
United States

HOME PAGE: http://sites.tufts.edu/willmasters

Tufts University - Department of Economics ( email )

Medford, MA 02155
United States

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