[From Bruce Abbott (950123.0915 EST)]
Rick Marken (950122.2200) --
I know that you have to know t and c and h in order to reconstruct d.
The problem was this: if you knew this then WHY did you ask the
question that set this all off, which was:Do the PCT-analysis programs you have written estimate the
reference value from the data?This question is puzzling even if we substitute "target value" for
"reference value". Why in the world would you imagine that we
"estimate" the value of t when we have it right there in the program?
At the time I wrote this, I was using the term "reference" to refer to both
the position of the target (the reference we ask the participant to adopt)
and to the reference actually used by the participant. However, as you
pointed out, these could be different. The first is known because it is set
by the program; the second is unknown, although we assume that it is
identical to the first because that's what we asked the participant to use.
But the reference actually adopted by the participant can be estimated from
the data under the assumption of certain constraints (e.g., that the
reference is constant over the period of observation being used to make the
estimate); I simply wanted to know if this is typically done in your
analyses and, if so, how. In my Minitab analyses of the threecv1 data, the
mean cursor position seems to do pretty well; the error thus far has never
been greater than about 1 pixel.
By the way, do I ever get to hear what you think these analyses of the
THREECV1 program data (particularly the multiple regression of
analysis of the proportion of variance in H accounted for by C1, C2 and
C3 when C3 is controlled) imply about the experimental and statistical
methods used in psychology? I've asked three times now. You're not
avoiding answering, are you?
No. Yes.
Actually, I'm waiting to see what happens when something more powerful than
multiple regression is applied to the data, specifically, path analysis.
Unfortunately, I'm not set up to do this at the moment. One of my
colleagues does a lot of this, and I'm waiting to see whether she thinks to
use it on her threecv1 data.
Regards,
Bruce