It’s funny how some people think that, because absence of evidence does not mean evidence of absence, it must mean evidence of presence…
(A graduate student in my department)
“The best researcher does not necessarily make the best teacher” — This is a contention that I have heard many times, made both by students and academics. It is difficult to dispute it, especially if phrased as above. We all have had bad experiences with university professors who may have been reputable scientists or scholars, but were simply not gifted classroom teachers. On the other hand, there exist individuals who do not possess or display any remarkable talent for research, but who nonetheless seem to prove able instructors, at least based on what have come to be accepted as reliable measures of teaching effectiveness. That this is true is hardly surprising — to any rule having to do with humans there are exceptions.
But, does the presence of exceptions undermine the general validity of the rule ? Does the above mean that there is no correlation between excellence in research and teaching effectiveness ? That universities need not hire valid researchers, if teaching becomes an increasingly important part of the job of an academic professor, even at a research university ?
Well, there is no question that many university administrators support that notion, and use it to justify cutting down on research staff, increasing instead the fraction of teaching-only personnel . It is a notion, however, which seems to run counter to the very philosophy underlying university education, not only in America but in most of the rest of the world, namely that research and teaching should go hand in hand.
I have been engaged in research and teaching at American universities for two decades, as a graduate student, postdoc and faculty. I am fairly convinced, based on my experience, the there is a strong correlation between effectiveness in research and teaching, i.e., a better researcher will generally (if not quite always), make a better (not, batter — thanks, Cherish) teacher as well.
Why is that ? In my opinion, again based on my own experience, because the insight into a specific topic, or subject, or area that one can achieve through research is unmatched by anything that one can obtain through mere textbook reading. The activity of doing research, exploring what is not known, has the effect of consolidating and deepening one’s understanding of what is known, the basic paradigms, the fundamental ideas, the methodology, the conceptual connections existing between various, often seemingly unrelated topics.
There is a difference between the understanding of a subject of someone who has diligently, meticulously gone through one or more textbooks (perhaps many times), worked out a large number of known and understood examples and carefully written understandable notes, and someone who has done research on that subject, i.e., played with it, pushed its boundaries, examined it from novel and different angles, attempted to tackle new and unresolved problems (or old ones but it a different ways) — the same difference that there exists between the knowledge of an engine of someone who has studied it on a manual, and someone who has taken the engine apart .
This is why, for example, I am more comfortable teaching Quantum Mechanics (QM) than Electricity and Magnetism (EM), even though I believe that I could teach a course in EM, if asked to do so. My research activity has made it necessary for me to be clear on at least some aspects of QM, to a degree that I cannot possibly achieve in EM simply by going through this torture.
Of course, the above is just my opinion — my “gut feeling”. It may well be wrong, or different than someone else’s opinion on the matter. The question arises of whether the correlation between teaching and research ability could be studied quantitatively, beyond individual opinions, and if so, how.
One idea that comes to mind is the following: in this day and age, university administrators are enamoured with numbers. Relentlessly one attempts to summarize a scholar’s teaching or research accomplishments through a single number. For teaching, that is the average score assigned to the person by students in their Course evaluation forms. Controversial as it remains among some, student evaluation of instruction (SEI) has widely come to be regarded as a reliable way of assessing teaching effectiveness.
What about research ? Identifying a single quantitative measure of research accomplishment is arguably even more problematic and controversial than for teaching, but that does not prevent some from trying. One of the most credible attempts is the introduction of the so-called h-index, which has probably as many detractors as it has supporters (see here, for instance) but is certainly gaining traction within the scientific community.
Assuming that both the above measure have some degree of validity, one could carry out a statistical analysis over a sufficiently large sample of researchers, and estimate the correlation between the two, to determine the degree to which tend to go together (does a higher-than-average value of one generally correlates with a higher-than-average value of the other ?).
A researcher’s h-index is publicly available through WebOfScience. What about SEI ? Some universities make scores available too, generally to students and faculty only. There are, however, web sites that allow virtually anyone to rate a college professor (see, for instance, this one). Unstructured and loosely run as these sites tend to be, the average scores that teachers receive appear to correlate reasonably well with those in “official” student evaluations administered by universities.
So, it may not be that difficult a thing to do, for anyone with both time and inclination — I am surprised it has not been done yet, to be honest.
 These people are much less expensive to hire, not only because they do not require any research infrastructure (e.g., a laboratory), but also because they are often employed on a part-time basis.
 Such a difference will typically emerge in the way the subject is presented, the emphasis placed on various aspects, the answers offered to questions — especially those that are slightly off-track (the type of questions that university students ask).