Sequential estimation of percent correct

Abstract

A sequential estimation and decision procedure is presented as an easily implemented alternative to adaptive methods. Unlike adaptive methods, the procedure does not alter stimulus values during the course of a run in order to converge at a desired level of performance. Instead, the procedure inspects a subject's cumulative performance at the end of each trial and, based on a set of well defined criteria, decides whether to continue or terminate the run. If the subject is performing well above or below the level of performance specified by the experimenter, the procedure stops the run. If the subject is operating near the specified level, the procedure continues the run (unless the specified maximum number of trials has been reached, in which case it stops the run). Regardless of why the procedure stops, a percent correct is estimated at the end of each run. In our experience, this procedure provides approximately a 50% saving in time over the fixed‐number‐of‐trials procedure. [Work supported by NIH.]