Calculate a mean effect size and its standard error.
Mazzucchelli, Kane, and Rees (2010) examined studies of behavioral activation as a way to improve feelings of subjective well-being. (They defined behavioral activation as €œintentional behavioral, cognitive, or volitional activity . . . intended to cultivate positive feelings, behaviors, and/or cognitions.€ They report data on 11 studies comparing treatment and control groups. These data are shown below broken down by those who showed minimal symptoms of depression and those who showed elevated symptoms. The results follow.

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Author Subgroup E (est.) nc (e)Hedges' Standard error Barlow86a levated Besyner79 Elevated Lovett88 Stark Van den HoutElevated Weinberg 12 .134 0.675 0.204 0.043 0.644 0.976 1.466 0.133 0.609 1410 0.378 0.523 0423 0.305 0439 0.371 0.467 0.524 0.352 0.195 0483 0.179 Elevated Elevated Elevated Elevated Wilson BarlowB6b Minimal Fordyce77 Minimal Fordyce83 Minial Reich8l Minimal 49 49 010z) way pues ueH "Wiap3nzzel-l uio.ll eia |00000000000 94913 24305092 For