In response to Ricky

Ricky:

You mention a study by McGoldrick et al. I just checked the EMDR website and could not find a citation nor did I find it in PsycInfo. Could you please provide the full citation? Thanks.

Also, before concluding the Ironson et al. favored EMDR, I suggest you compute the within-group effect sizes for EMDR and PE. When I did so, I obtained an effect size after 6 treatment sessions (3 planning plus 3 active treatment) for PE of 2.18, compared to 1.53 for EMDR. How can this be? I addressed this in an earlier post (back on 1/26/03) but thanks to the magic of cut and paste, it is reproduced below. By the way, Ironson et al. altered EMDR by adding in vivo exposure, thereby reducing the procedural differences between PE and EMDR.
From 1/26/03:
Ironson et al., 2002 - EMDR plus in vivo exposure instructions was equivalent to exposure therapy. There are claims that there was evidence of superiority for EMDR in terms of greater efficiency. Specifically, the report that more people in the EMDR group had 70% reduction in PTSD severity (measured by the PSS-SR) than in exposure therapy. However, I suggest that it is a statistical artifact.
The amount of change after three prep sessions and three treatment sessions was nearly identical for the two treatments. However, the percent change in EMDR was greater. Mathematically, the only way for this to be true is if the denominator of the percent ratio (the pretreatment score in this case) for EMDR was smaller than for exposure therapy. Specifically, the average pretreatment PSS-SR score for exposure was 34.56, the average posttreatment score was 15.78, resulting in an 18.78 point change, which translates to an average 54.3 percent reduction. In EMDR, the pretreatment score was 26.58 and the posttreatment score was 9.1, for a mean reduction of 17.48 points, which is numerically SMALLER than the reduction for exposure therapy, but it translates to a larger average percent change (65.8%). Therefore, I don't believe their conclusions about efficiency are warranted and that both treatments were roughly equivalent.

Replies:

View from 30,000 feet up, by Sandra Paulsen Inobe PhD, 04/21/03 In response to Shawn, by Ricky Greenwald, 04/22/03 Not quite so fast, by Cahill, 04/23/03 That's my point too, by Ricky Greenwald, 04/23/03 Re:Here's the point, by Landry, 04/23/03 Re:Here's the point, by Sandra Paulsen Inobe PhD, 04/24/03 Re:Here's the point, by Realist, 04/24/03 Different methodological positions, by Cahill, 04/24/03 Re:Different methodological positions, by Realist, 04/24/03 Re:Different methodological positions, by Sandra Paulsen Inobe PhD, 04/25/03 Re:Here's the point, by Carol Ann Rowland, MSW, RSW, 04/24/03 Re:Here's the point, by Ricky Greenwald, 04/25/03 researcher allegiance, by Ricky Greenwald, 04/25/03 Re:Here's the point, by Landry, 04/26/03 Re:Here's the point, by Ricky Greenwald, 04/28/03 Something unique happening in EMDR?, by Cahill, 05/01/03 Re:Something unique , by Fred H., 05/09/03 Let's leave innuendo out of the discussion, by Cahill, 04/26/03 Re:Let's leave innuendo out of the discussion, by Ricky Greenwald, 04/28/03 Devilly & Spence, logical analyses and other stuff, by Cahill, 05/01/03 Re:Devilly & Spence, logical analyses and other stuff, by Realist, 05/02/03 What is EMDR?, by Ricky Greenwald, 04/23/03 Re:What is EMDR?, by Cahill, 05/01/03

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