[From Bruce Abbott (950123.1800 EST)]
Rick Marken (950123.1010)
Let me show your complete statement:
Do the PCT-analysis programs you have written estimate the reference
value from the data? When the data set contains only cursor and handle
positions, (i.e., lacks the disturbance tables), the disturbance values
can be calculated exactly only if the reference values are knownIf you just wanted to know whether reference (or target) value estimation is
typically done in our analyses, then why did you go on to say that
disturbance values "can be calculated exactly only if the reference [target]
values are known". Given the close proximity of your question about estimates
of reference [target] values to your statement about needing these values to
reconstruct d, it seemed to me (and to Tom too, apparently) that you thought
you had to estimate the reference [target] value (rather than just look it up
in the program code) in order to reconstruct d. That is, it seemed like you
didn't understand that c = h+c+t.
I was assuming that r = t. If t is not included in the data set and r = t,
then the estimate of r will give you something close to t. I was also
wondering whether, in the more general case, you estimated the subject's
reference as a matter of course in your analysis (independent of its
possible use to substitute for t in the calculation of disturbances). After
the post, I decided that using the estimate of r as a substitute for t was
not a good idea and added the target positions as the first line of the data
file. So really, there are two issues here, one specifically addressed to
the problem I faced concerning what data I needed to save in this particular
program and the other the more general issue of estimating r to determine
what reference the participant was actually using.
I think we've beat this dead horse enough. Bill P. says you now have TP 7;
have you had a chance to run 3CV1 and PCTAN yet?
Regards,
Bruce