Re: Then EMDR isn't science

Even though your comments deserve no reply I would like to clarify the issue of power that you rose because this concept was mentioned and is important. You insinuate that I do not know what I am talking about. While it has been some time since my stats courses I think that my statements are theoretically correct.

For the sake of those who do not know, power refers to the probability of rejecting a false null hypothesis. In plain English, this means the power of an analysis to find an effect when it actually exists. Low sample size can reduce power, therefore reducing your chances of finding an effect when one exists. However, something that also influences power is the effect size of the observed difference. When the effect size is large, all thinks being equal, you will increase your probability of finding a significant difference if one exists. You may be asking how this relates to EMDR. EMDR is claimed to be a treatment that is vastly more powerful (not in the same sense of statistical power but related to effect size) than any other treatment because it can produce miraculous and superior benefits compared with other methods. Large effect sizes can theoretically be picked up even if sample sizes are small. In reverse, then, large sample sizes can pick up paltry effects. Now, I have not done the power analyses on the data to know what sample size is needed but theoretically smaller samples should be able to pick up the supposedly large effects produced by EMDR if they actually existed. Because eye movements are the only, and I stress only, part of EMDR that is truly new, controlling for eye movements is a legitimate test of EMDR in my opinion. If such "bilateral stimulation" was the "power tool" that it is claimed to be, these results should be easily demonstrated.

If you see anything "confused" about the above statements "a contributor" please post a reply that actually adds some substance to the dialogue.

Replies:

Re: EMDR is science but Brian has a short memory, by Tired of more recycled rhetoric, 5/23/00 Let's Move On (no message), by Sandra Paulsen, Ph.D., 5/23/00 Let's Move On, by Sandra Paulsen, Ph.D., 5/23/00

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