But has any reliable correlation ever been established between research productivity and poor teaching? To the contrary, nearly all of the reliable studies “clearly indicate,” in the words of John Hattie and Herbert W. Marsh, that “Good researchers are neither more nor less likely to be effective teachers than are poor researchers.” (Such studies reinforce my own local observations that the least-committed teachers very often prove to be the least-productive researchers, and many of the most dedicated researchers are terrific teachers.)There are several possibilities here.
A researcher is low in productivity, but is an excellent teacher.
A researcher is high in productivity, but is a poor teacher.
A researcher is strong in both research and teaching.
A researcher is weak in both areas.
A researcher is mediocre in both categories, or moderately strong in both, or slightly better in one than the other, depending on the exact measuring device...
For those weak, or strong, in both areas, the cause is likely to be similar. They might be strong conscientious performers in whatever they do. Or not. Even in the case of negative correlation, we don't know if this is a coincidence or a causation. For example, is the good teacher good because she neglects research, or because she is simply better at one thing than another? Is the bad teacher bad because he cares too much about research?
If it possible to excel in both areas, shouldn't that be encouraged?
Of course, teaching fewer classes frees up time for research, but I am talking more about quality rather than quantity. Another myth is that those who publish more write articles of less quality.