Don <[EMAIL PROTECTED]> wrote:
I'm currently just concerned with whether the pre-treatment scores of those
in control group, and those in the treatment group are ths same. So for this
exercise, isn't it true to say that I have data for the entire population of
interest, and therefore sigma is known?
Radford Neal wrote:
The scores are either the same or they're not. Most likely not, if theI agree with Dr Neal. Perhaps you should consider using the analysis of covariance to evaluate group difference, using the baselines measure as the covariate.
scores are approximately continuous. There's no need for any test.
I doubt this is your real question, however.
Are you worried that a supposedly random assignment to treatment and
control groups wasn't really random? If so, you could do a large number
of actually random assignments and compare the difference in scores for
the actual assignment with the distribution for random assignments.
Or are you worried that even though the assignment was random, it by chance produced unbalanced groups? If so, seeing whether some test or
other rejects a hypothesis that you know to be true is not a sensible
approach. You just need to analyse the data in a way that doesn't
rely on this (eg, include the score as an explanatory variable in a
regression model).
SR Millis
.
.
=================================================================
Instructions for joining and leaving this list, remarks about the
problem of INAPPROPRIATE MESSAGES, and archives are available at:
. http://jse.stat.ncsu.edu/ .
=================================================================
