Figure highlights deleterious effects of ceiling effects on commonly used effect size dp using both Henry et al.  data set and much larger data set included in the present study.
Panel A shows dp calculated by Henry et al.  as a function of older adults performance (test difficulty) for laboratory conditions that were free of age-confounds only (color of the circles indicate prospective memory subdomain: red = event-cued prospective memory proper, blue = event-cued vigilance, green = time-cued vigilance). Panel A highlights that the size of age declines measured by effect size index dp decreases as performance of older adults increases, as the test becomes easier and data are more afflicted by ceiling effects. Panel B demonstrates this deleterious effect of ceiling effects on dp using much larger data set identified for the current study. Panel C highlights that even age declines measured by dprobit are dependent on the test difficulty but, consistent with previous simulations , less so. Finally, Panel D highlights that dp underestimates the size of age decline relative to dprobit; age declines measured by dp are smaller then age declines measured by dprobit.