Hacker; Who's Got the IV?

[from Gary Cziko 930401.0450 GMT]

Ken Hacker [930329], you said:

I understand and appreciate the point about rejecting the IV-DV
view for all human behaviors, but are there not some questions about
human behavior where they are useful -- if we take causality out of
the assumptions? For example, if I test 2 groups (which I will be
doing in the fall) of students, one with one type of learning
program and one with another, and see what differences there are in
knowledge retention, recall, etc., what is wrong with what I am
doing? The answer is NOTHING is wrong with it if I am simply
comparing retention and recall differences by program differences.
Can I go deeper into student behaviors, perceptions, control? YES,
of course, but I may not need to in order to answer my questions.

Bill Powers has already mentioned some potential problems with using an
indepenent groups method for a study like this. I would like to consider
the very idea of what an "independent" variable is.

There may well be nothing wrong with this approach if in fact you have a
true independent variable. But is the program variable really an
independent variable? Wouldn't this mean that the students would have
absolutely no control over the learning environment? They could not ask
questions of the lecturer in the "lecture" condition and they could not
influence the computer program in the "computer" condition.

And finding a "significant" difference between the two groups does not
necessarily indicates WHY one group did better than the other. Perhaps the
lectures were so good that the students (or at least some of them) in that
group didn't study hard outside of class and consequently did not do as
well as the test. While the computer group had such a dreadful experience
that they put lots of outside study time into the course. Now you can try
to control these factors, too (try to make them "independent" variables),
but then your programs become more and more bizarre and less like any
actual educational program.

It seems to be that good teachers and good educational programs are most
definitely NOT independent variables. Good teachers are sensitive to the
individual needs of their students. Good computer courseware allows the
students to direct the pace and often the direction of the instruction.
And good students (those who want to learn new skills and develop their
knowledge) will be successful in spite of the variations in teachers and
programs they will encounter.

I suppose you could argue that even though the students will have SOME
control over the so-called independent variable, there will still be
important differences between the two treatments, and this may well be the
case. But I would predict that you will find considerable overlap between
the two methods in students' learning and that almost all of the variation
in outcome will be due to individual differences in reference settings in
the learners (the true independent variable), and not to the method used to

I'd be interested in seeing how your study turns out so we can have real
data to discuss. If you don't want to wait, why don't you provide the
reference to any educational study which uses IV-DV methodology (and
hopefully group statistics as well) which you feel has provided valuable
information about teaching and/or learning and we could discuss that in the


Gary Cziko Telephone: 217-333-8527
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