A Cautionary Tale of Evaluating Identifying Assumptions: Did Reality TV Really Cause a Decline in Teenage Childbearing?

31 Pages Posted: 1 Aug 2018 Last revised: 17 Jul 2021

See all articles by David Jaeger

David Jaeger

City University of New York (CUNY)

Theodore Joyce

CUNY Baruch College - Zicklin School of Business; National Bureau of Economic Research (NBER)

Robert Kaestner

University of Chicago; National Bureau of Economic Research (NBER)

Date Written: July 2018

Abstract

Evaluating policy changes that occur everywhere at the same time is difficult because of the lack of a clear counterfactual. Hoping to address this problem, researchers often proxy for differential exposure using some observed characteristic in the pre-treatment period. As a cautionary tale of how difficult identification is in such settings, we re-examine the results of an influential paper by Melissa Kearney and Phillip Levine, who found that the MTV program 16 and Pregnant had a substantial impact on teen birth rates. In what amounts to a difference-in-differences approach, they use the pre-treatment levels of MTV viewership across media markets as an instrument. We show that controlling for differential time trends in birth rates by a market’s pre-treatment racial/ethnic composition or unemployment rate causes Kearney and Levine’s results to disappear, invalidating the parallel trends assumption necessary for a causal interpretation. Extending the pre-treatment period and estimating placebo tests, we find evidence of an “effect” long before 16 and Pregnant started broadcasting. Our results highlight the difficulty of drawing causal inferences from national point-in-time policy changes.

Suggested Citation

Jaeger, David and Joyce, Theodore J. and Kaestner, Robert, A Cautionary Tale of Evaluating Identifying Assumptions: Did Reality TV Really Cause a Decline in Teenage Childbearing? (July 2018). NBER Working Paper No. w24856, Available at SSRN: https://ssrn.com/abstract=3218108

David Jaeger (Contact Author)

City University of New York (CUNY)

Theodore J. Joyce

CUNY Baruch College - Zicklin School of Business ( email )

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National Bureau of Economic Research (NBER) ( email )

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Robert Kaestner

University of Chicago ( email )

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National Bureau of Economic Research (NBER)

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