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Instrumental variables based on twin births are by definition not valid (v.3.0)

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  • Öberg, Stefan

Abstract

Twin births are a well-known and widespread example of a so-called “natural experiment”. Instrumental variables based on twin births have been used in many studies to estimate the causal effect of the number of children on the parents or siblings. I use the potential outcomes framework to show that these instrumental variables do not work as intended. They are fundamentally flawed and will always lead to severely biased estimates without any meaningful interpretation. This has been overlooked in previous research because too little attention has been paid to defining the treatment in this natural experiment. I analyze three different possible interpretations of the treatment and show that they all lead to inherent violations of the necessary assumptions. The effect of the number of on the parents or siblings is a policy relevant and theoretically important issue. The scientific record should therefore be corrected to not lead to misguided decisions.

Suggested Citation

  • Öberg, Stefan, 2018. "Instrumental variables based on twin births are by definition not valid (v.3.0)," SocArXiv zux9s, Center for Open Science.
    • Handle: RePEc:osf:socarx:zux9s
    DOI: 10.31219/osf.io/zux9s
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    1. Joshua D. Angrist & Alan B. Krueger, 2001. "Instrumental Variables and the Search for Identification: From Supply and Demand to Natural Experiments," Journal of Economic Perspectives, American Economic Association, vol. 15(4), pages 69-85, Fall.
    2. Tabea Bucher-Koenen & Helmut Farbmacher & Raphael Guber & Johan Vikström, 2020. "Double Trouble: The Burden of Child-rearing and Working on Maternal Mortality," Demography, Springer;Population Association of America (PAA), vol. 57(2), pages 559-576, April.
    3. Sonia Bhalotra & Damian Clarke, 2019. "Twin Birth and Maternal Condition," The Review of Economics and Statistics, MIT Press, vol. 101(5), pages 853-864, December.
    4. Mahdi Majbouri, 2019. "Twins, family size and female labour force participation in Iran," Applied Economics, Taylor & Francis Journals, vol. 51(4), pages 387-397, January.
    5. Helena Holmlund & Helmut Rainer & Thomas Siedler, 2013. "Meet the Parents? Family Size and the Geographic Proximity Between Adult Children and Older Mothers in Sweden," Demography, Springer;Population Association of America (PAA), vol. 50(3), pages 903-931, June.
    6. Anna Baranowska-Rataj & Anna Matysiak, 2016. "The Causal Effects of the Number of Children on Female Employment - Do European Institutional and Gender Conditions Matter?," Journal of Labor Research, Springer, vol. 37(3), pages 343-367, September.
    7. Guo, Rufei & Li, Hongbin & Yi, Junjian & Zhang, Junsen, 2018. "Fertility, household structure, and parental labor supply: Evidence from China," Journal of Comparative Economics, Elsevier, vol. 46(1), pages 145-156.
    8. James J. Heckman & Sergio Urzua & Edward Vytlacil, 2006. "Understanding Instrumental Variables in Models with Essential Heterogeneity," The Review of Economics and Statistics, MIT Press, vol. 88(3), pages 389-432, August.
    9. Timothy J. Hatton & Richard M. Martin, 2010. "The effects on stature of poverty, family size, and birth order: British children in the 1930s," Oxford Economic Papers, Oxford University Press, vol. 62(1), pages 157-184, January.
    10. Sonia Bhalotra & Damian Clarke, 2020. "The Twin Instrument: Fertility and Human Capital Investment," Journal of the European Economic Association, European Economic Association, vol. 18(6), pages 3090-3139.
    11. Idriss Fontaine, 2018. "L’effet causal du nombre d’enfants sur l’offre de travail des mères : le cas de la France métropolitaine et de ses départements d’outre-mer," Revue économique, Presses de Sciences-Po, vol. 69(5), pages 869-898.
    12. Angrist, Joshua D & Evans, William N, 1998. "Children and Their Parents' Labor Supply: Evidence from Exogenous Variation in Family Size," American Economic Review, American Economic Association, vol. 88(3), pages 450-477, June.
    13. Guido W. Imbens, 2010. "Better LATE Than Nothing: Some Comments on Deaton (2009) and Heckman and Urzua (2009)," Journal of Economic Literature, American Economic Association, vol. 48(2), pages 399-423, June.
    14. James J. Heckman, 2010. "Building Bridges between Structural and Program Evaluation Approaches to Evaluating Policy," Journal of Economic Literature, American Economic Association, vol. 48(2), pages 356-398, June.
    15. Seema Jayachandran & Rohini Pande, 2017. "Why Are Indian Children So Short? The Role of Birth Order and Son Preference," American Economic Review, American Economic Association, vol. 107(9), pages 2600-2629, September.
    16. James Heckman, 1997. "Instrumental Variables: A Study of Implicit Behavioral Assumptions Used in Making Program Evaluations," Journal of Human Resources, University of Wisconsin Press, vol. 32(3), pages 441-462.
    17. Rannveig Hart & Sara Cools, 2019. "Identifying interaction effects using random fertility shocks," Demographic Research, Max Planck Institute for Demographic Research, Rostock, Germany, vol. 40(10), pages 261-278.
    18. Julie Moschion, 2013. "The Impact of Fertility on Mothers' Labour Supply in Australia: Evidence from Exogenous Variation in Family Size," The Economic Record, The Economic Society of Australia, vol. 89(286), pages 319-338, September.
    19. Joseph Boniface Ajefu, 2019. "Does having children affect women’s entrepreneurship decision? Evidence from Nigeria," Review of Economics of the Household, Springer, vol. 17(3), pages 843-860, September.
    20. repec:adr:anecst:y:2010:i:99-100:p:10 is not listed on IDEAS
    21. Joshua D. Angrist & Victor Lavy & Analia Schlosser, 2005. "New Evidence on the Causal Link Between the Quantity and Quality of Children," NBER Working Papers 11835, National Bureau of Economic Research, Inc.
    22. Anna, Petrenko, 2016. "Мaркування готової продукції як складова частина інформаційного забезпечення маркетингової діяльності підприємств овочепродуктового підкомплексу," Agricultural and Resource Economics: International Scientific E-Journal, Agricultural and Resource Economics: International Scientific E-Journal, vol. 2(1), March.
    23. Marc Frenette, 2011. "How does the stork delegate work? Childbearing and the gender division of paid and unpaid labour," Journal of Population Economics, Springer;European Society for Population Economics, vol. 24(3), pages 895-910, July.
    24. Helena Holmlund & Helmut Rainer & Thomas Siedler, 2013. "Meet the Parents? Family Size and the Geographic Proximity Between Adult Children and Older Mothers in Sweden," Demography, Springer;Population Association of America (PAA), vol. 50(3), pages 903-931, June.
    25. Joshua Angrist & Victor Lavy & Analia Schlosser, 2010. "Multiple Experiments for the Causal Link between the Quantity and Quality of Children," Journal of Labor Economics, University of Chicago Press, vol. 28(4), pages 773-824, October.
    26. Joshua D. Angrist & Jörn-Steffen Pischke, 2015. "The path from cause to effect: mastering 'metrics," CentrePiece - The magazine for economic performance 442, Centre for Economic Performance, LSE.
    27. Bronars, Stephen G & Grogger, Jeff, 1994. "The Economic Consequences of Unwed Motherhood: Using Twin Births as a Natural Experiment," American Economic Review, American Economic Association, vol. 84(5), pages 1141-1156, December.
    28. Martin Kolk, 2015. "The causal effect of an additional sibling on completed fertility: An estimation of intergenerational fertility correlations by looking at siblings of twins," Demographic Research, Max Planck Institute for Demographic Research, Rostock, Germany, vol. 32(51), pages 1409-1420.
    29. Joshua Angrist & Alan Krueger, 2001. "Instrumental Variables and the Search for Identification: From Supply and Demand to Natural Experiments," Working Papers 834, Princeton University, Department of Economics, Industrial Relations Section..
    30. Anna Baranowska-Rataj & Xavier de Luna & Anneli Ivarsson, 2016. "Does the number of siblings affect health in midlife? Evidence from the Swedish Prescribed Drug Register," Demographic Research, Max Planck Institute for Demographic Research, Rostock, Germany, vol. 35(43), pages 1259-1302.
    31. Guo, Rufei & Yi, Junjian & Zhang, Junsen, 2017. "Family size, birth order, and tests of the quantity–quality model," Journal of Comparative Economics, Elsevier, vol. 45(2), pages 219-224.
    32. Chen, Qihui, 2017. "Relaxed population policy, family size and parental investments in children’s education in rural Northwestern China," International Journal of Educational Development, Elsevier, vol. 54(C), pages 39-50.
    33. Dasgupta, Kabir & Solomon, Keisha T., 2018. "Family size effects on childhood obesity: Evidence on the quantity-quality trade-off using the NLSY," Economics & Human Biology, Elsevier, vol. 29(C), pages 42-55.
    34. Imbens,Guido W. & Rubin,Donald B., 2015. "Causal Inference for Statistics, Social, and Biomedical Sciences," Cambridge Books, Cambridge University Press, number 9780521885881.
    35. Julie Moschion, 2010. "Reconciling Work and Family Life: The Effect of the French Paid Parental Leave," Annals of Economics and Statistics, GENES, issue 99-100, pages 217-246.
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    Cited by:

    1. Öberg, Stefan, 2019. "Too LATE for Natural Experiments: A Critique of Local Average Treatment Effects Using the Example of Angrist and Evans (1998)," SocArXiv acdv4, Center for Open Science.
    2. Öberg, Stefan, 2021. "Treatment for natural experiments: How to improve causal estimates using conceptual definitions and substantive interpretations," SocArXiv pkyue, Center for Open Science.

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