A simple pre-post comparison

Say you are looking at a change in teenagers’ sense of ‘internal locus of control = ILC’, i.e. whether thy think they are in control of their behavior (high ILC, a max. of 5) or they are not in control (low ILC, min of 1).
You are getting a group of youth to participate in a program, and measure their ILC before (baseline) and after your intervention/treatment, and compare to another group that was not so lucky to find you… The raw numbers would look like the figure below; the question is: DID IT WORK?
The answer can be… 15 different ones (at least using alternative causal modeling): 8 of these ‘tests’ say YES, it did, 7 of them would say NO! So, should you give it a try in you own community based on this ‘evidence’? I’d say you should, mainly because the 7 ‘bad’ models had no statistical power to detect the effect…

Internal Locus of Control intervention effects

The lesson here? There are many models/tests that can answer a simple question, some are better, others worse, one should know HOW to compare the models to be certain the conclusion is sound. Simple? Useful?
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