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Happy birthday? An observational study
  1. Gabrielle E Kelly1,
  2. Cecily C Kelleher2
  1. 1 School of Mathematics and Statistics, University College Dublin, Dublin, Ireland
  2. 2 Physiotherapy and Sports Science, University College Dublin, School of Public Health, Dublin, Ireland
  1. Correspondence to Dr Gabrielle E Kelly, School of Mathematics and Statistics, University College Dublin, Dublin 4, Ireland; gabrielle.kelly{at}


Background Previous studies show contradictory findings on the relationship between birthday and deathday, in particular whether people postpone death until after their birthday. We examine the phenomenon in eight groups of famous people.

Methods Birthday and deathday for the following groups were recorded: British prime ministers, US presidents, Academy Award best actor, best female actor, best director, Nobel Prize winners, Wimbledon men’s and ladies' singles winners, all from when records began. For each group, the difference in days between the deathday and birthday was calculated. Under the hypothesis of no association, one can expect the difference to have a uniform distribution. This is assessed using goodness-of-fit tests on a circle.

Results All groups showed some departure from the uniform and it occurred around the birthday in all groups. British prime ministers, US presidents, Academy Award actors and directors, Nobel Prize winners and Wimbledon men show a ’dip' in deaths around the birthday. The length of the ’dip' varied between the groups and so they gave different p-values on different test statistics. For Academy Award female actors and Wimbledon ladies, there was rise in deaths before and after birthday. When Nobel Prize winners were subdivided into their categories, Science and Literature had a ’dip' around the birthday, but not other categories.

Conclusions We conclude ’something' happens to deathday around the birthday. Some groups of famous people show a ’dip' in death rate around the birthday while for others, particularly women, the association is in the opposite direction.

  • psychological stress
  • psychosocial factors
  • mortality
  • biostatistics
  • directional statistics

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  • Contributors GEK designed the study, and conducted the data collection and management, analysis, interpretation of the data and preparation of the manuscript. CCK aided in the interpretation of data; in the writing of the report; and in the decision to submit the article for publication. GEK supervised the study and is the guarantor. The research conducted was independent of any involvement of sponsors. Both authors had full access to all of the data in the study and can take responsibility for the integrity of the data and the accuracy of the data analysis.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement Any data used are freely available on the Worldwide Web.

  • Correction notice This article has been corrected since it first published online. In the Introduction the line'… examined >12 million records of Swiss mortalities…' has been changed to'… examined >2 million records of Swiss mortalities…'