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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