RT Journal
A1 Fontanarosa PB, Krakow B, Hollifield M, Warner TD
T1 PLacebo effect in posttraumatic stress disorders
JF JAMA
JO JAMA
YR 2000
FD August 2
VO 284
IS 5
SP 563
OP 563
DO 10.1001/jama.284.5.561
UL http://dx.doi.org/10.1001/jama.284.5.561
AB 
However, a closer examination of the data (Tables 3 and 4), using effect
size calculations (modified Cohen d values estimated
from the SDs provided), suggests an alternative explanation for the observed
treatment effects. Large effect sizes were demonstrated for both sertraline
and placebo groups for total Clinician Administered PTSD, Part 2 (CAPS-2)
(sertraline, d = 1.45 vs placebo, d = 1.0), total Impact of Event (sertraline, d
= 0.97 vs placebo, d = 0.74), and Clinical Global
Impression-Severity (sertraline, d = 1.18 vs placebo, d = 0.83), as well as for CAPS-2 intrusion (sertraline, d = 1.05 vs placebo, d = 0.76),
avoidance (sertraline, d = 1.35 vs placebo, d = 0.95), and arousal (sertraline, d = 1.27 vs placebo, d = 0.85) scales. In
taking the customary difference between the 2 groups by subtracting the placebo
effect size, the net sertraline treatment effects are much smaller, ranging
from 0.24 to 0.45 for the above measures.