Optional Stopping

Definition: The practice of (repeatedly) analyzing data during the data collection process and deciding to stop data collection if a statistical criterion (e.g. p-value, or bayes factor) reaches a specified threshold. If appropriate methodological precautions are taken to control the type 1 error rate, this can be an efficient analysis procedure (e.g. Lakens, 2014). However, without transparent reporting or appropriate error control the type 1 error can increase greatly and optional stopping could be considered a Questionable Research Practice (QRP) or a form of p-hacking.

Related terms: <a href='/glossary/p-hacking/'>P-hacking</a>, Questionable Research Practices or Questionable Reporting Practices (QRPs), Sequential testing

References: Beffara Bret et al. (2021), Lakens (2014), Sagarin et al. (2014), & Schönbrodt et al. (2017)

Drafted and Reviewed by: Brice Beffara Bret, Bettina M. J. Kern, Ali H. Al-Hoorie, Helena Hartmann, Catia M. Oliveira, Sam Parsons

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