Title | Ethics and sample size. |
Author | Bacchetti P, Wolf LE, Segal MR, McCulloch CE |
Year | 2005 |
Journal | Am J Epidemiol |
Volume | 161 |
Issue | |
Pages | 105-110 |
Publisher | |
Link_for_PDF_for_Education | |
Link for Open Access | |
DOI | |
Link for DOI | |
Web_Access_Paper | http://aje.oxfordjournals.org/content/161/2/105.full |
Contributed_by | Peter Bacchetti |
Commentary | This presented a refutation the argument that having too small a sample size makes studies unethical because they do not produce enough scientific or clinical value to justify the burdens accepted by participants. It showed that the ratio of projected value to participant burden can only worsen as sample size increases, because power (and other measures of projected value) have diminishing marginal returns as a function of sample size, while the projected total burden on participants increases in proportion to sample size. The exposition used the equivalence that total study value exceeds total participant burden if and only if value per participant exceeds burden per participant. An accompanying commentary raised objections, notably arguing that projected value could have increasing marginal returns with sample size if participants' altruistic satisfaction were included in projected study value, because they often value their own contribution without consideration of how small a fraction they themselves made up of the total sample. A rejoinder addressed the objections, in particular noting that participants' altruistic satisfaction cannot be included as part of a study's projected scientific or clinical value when assessing whether it is sufficient to justify the participant burden. Later work established diminishing marginal returns for a wide array of measures of projected study value that have been proposed for use in sample size planning (Bacchetti P, McCulloch CE, Segal MR. Simple, defensible sample sizes based on cost efficiency. Biometrics, 64: 577-594, 2008), including both frequentist and Bayesian perspectives, as well as both decision theoretic and evidential frameworks. Further discussion of the issues is available here. |
Additional_Information | |
Reference_Subject | Biostat_Ethics |
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