Month-of-Birth Effects on Skills and Skill Formation

76 Pages Posted: 11 Aug 2020 Last revised: 17 May 2023

See all articles by Shintaro Yamaguchi

Shintaro Yamaguchi

University of Tokyo - Graduate School of Economics

Hirotake Ito

CyberAgent, Inc

Makiko Nakamuro

Keio University

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Date Written: May 11, 2023


We estimate month-of-birth effects on cognitive and noncognitive skills, as well as factors relevant to skill formation. Our estimates indicate that younger students in a given grade cohort have lower cognitive and noncognitive skills. To shed light on the underlying mechanisms, we also examine children's time use and interpersonal relationships. We find evidence of compensatory investment in cognitive skills by younger children, however, they are also more likely to have poor-quality relationships with their classmates and teachers, which may harm the long-term development of noncognitive skills. Our findings on skill formation have implications for efficiency and equity.

Keywords: relative age effect, cognitive skill, non-cognitive skill

JEL Classification: I210, I240, J24

Suggested Citation

Yamaguchi, Shintaro and Ito, Hirotake and Nakamuro, Makiko, Month-of-Birth Effects on Skills and Skill Formation (May 11, 2023). Available at SSRN: or

Shintaro Yamaguchi (Contact Author)

University of Tokyo - Graduate School of Economics ( email )


Hirotake Ito

CyberAgent, Inc ( email )

Makiko Nakamuro

Keio University

2-15-45 Mita
Tokyo, 108-8345

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