One of the questions often raised in the debate over outcome-based education (OBE) is whether any research supports this approach. To my knowledge, no studies directly compare students in OBE classes or schools to students in similar control schools. This being the case, advocates on both sides of the debate have attempted to make inferences about OBE from other areas of research.
In particular, opponents of OBE have often cited my 1987 review of research on group-based mastery learning as evidence that OBE is ineffective (Slavin 1987). Such a comparison is inappropriate. The research I reviewed involved strategies in which teachers teach a series of lessons and then give a formative test. Students who score below a pre-established mastery criterion (say, 80 percent correct) then receive a few hours of corrective instruction, while others do enrichment activities. A second summative test is then given, and the cycle may be repeated if many students still score below the mastery criterion.
My review was a response to Bloom's assertion that mastery learning could produce gains of two standard deviations (1984). He based his claim on brief laboratory studies in which students who did not master the material on the first test received substantial additional time, one-to-one tutoring, or both. I concluded that in more realistic settings, mastery learning had far less impressive results. Group-based mastery learning often produced modest increases in performance on tests closely tied to the material being taught, but achievement on broader-based measures did not improve.
I hope it is clear that my review of group-based mastery learning had nothing to do with OBE. In its broadest definition I find it hard to oppose the concept of OBE; who would argue that educational programming should not be based on some idea of what we want students to know or be able to do? On the other hand, it is legitimate to debate what kinds of outcomes we want, how they will be measured, and what happens if students don't achieve them.
In the absence of research, OBE proposals being made by various states and districts must be evaluated on their details. Certainly, the whole community should decide what schools or students should be held accountable for. Without the details of these proposals, I don't have a position on any of them, but I do know that my mastery learning review has nothing to do with the issue one way or the other.