Brett:
In addition to everything else you do, be sure to track data for individual
cases. If there is an underlying function (e.g. steady decline followed by
precipitous drop), averging data will obscure the function. I remember seeing
discrimination learning curves from grouped data that used to show a gradual
rise over trials, but individual functions all showed chance performance until
they "learned it" in one trial. You may or may not want to publish the
individual curves, but, at the very least they can be informative in the early
stages of a learning project. Good luck with the research.
"Magill, Brett" wrote:
> I am planning to design a study of an educational program. Of interest is
> the decay over time of knowledge and skills learned through the program.
> Specifically, we want to know if there is a point in time when the rate of
> decay changes (a steady drop turns into a crash). In addition, we want to
> be able to determine at what point the level of knowledge/skills drops below
> a certain standard. At issue at what point is additional education
> necessary. The argument as it appears in the literature is 1 or 2 years.
>
> So, my question is what is the best design/method for approaching this
> question and with this design, what is the best analytic method? Right now,
> we are considering a longitudinal study with data collection pre/post
> education with follow-up every three months for two years. With this
> design, we could use repeated measures ANOVA. It has also been suggested
> that survival analysis might have some applicability here. In addition, I
> understand that one can use a squared term in a model (for example time
> along with time^2) to examine a change in the rate of decay.
>
> What I am looking for is references to any of these topics--especially if
> they are applied to a similar question as above. In addition, I welcome any
> other suggestions about how to approach this topic--either methodologically
> or statistically.
>
> Regards,
> Brett
>
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--
---------------------------------------------------------------
John W. Kulig [EMAIL PROTECTED]
Department of Psychology http://oz.plymouth.edu
Plymouth State College tel: (603) 535-2468
Plymouth NH USA 03264 fax: (603) 535-2412
---------------------------------------------------------------
"The only rational way of educating is to be an example - if
one can't help it, a warning example." A. Einstein, 1934.
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