Re: Media violence

[Mark A. Casteel]

Actually, it's a comprehensive review of the correlational, experimental, and meta-analytic studies that have been published through 2003. It's a fascinating article, especially the story about how it made its way to PSPI. The article was originally intended to be one part of a series of reports commissioned by the Surgeon General in 2000 dealing with the overall topic of youth violence. After submitting the report, the original authors received it back in a form that they hardly recognized. After additional wrangling, the final report was finally subsumed into another report and appeared as an Appendix without any author names. As a result, what made its way to PSPI is the original report, although it has been modified for the format of PSPI and includes the most recent research. The Editorial and the Author's Note tell an interesting tale about the intersection of policy and science, and if nothing else, I urge TIPS readers to read the introductory comments. -- Mark

At 02:16 PM 3/25/2004 -0500, you wrote:

This is a metanalysis of past research I take it? Rosenthal had an article in (I think) _Psychological Methods_ recently about how to convert t-tests into r-equivalent effect size measures (based on a talk I saw him give at APA a couple of years back). It's as reasonablea  thing to do as r is a reasonable statistic. I'd have to know the knid of data they're converting to know for certain, but my suspicion is that r would tend to underestimate effects because it is sensitive to the linearity of the relationship (i.e., it misses non-linear relationships) and it tends to be depressed by restricted ranges (i.e., less than 9 or so *used* scale values).

Regards,
--
Christopher D. Green
Department of Psychology
York University
Toronto, Ontario M3J 1P3
Canada

office: 416-736-5115 ext. 66164
fax: 416-736-5814
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don allen wrote:

Hi Tipsters-
 
I need some help in deciphering the latest issue of Psychological Science in the Public Interest (Vol. 4(3), 2003) on "The Influence of Media Violence on Youth".  On page 84 the authors state,
 
"There are several commonly used measures of effect size, any of which can be applied to experimental, correlational and longitudinal types of studies. To provide a common metric for this discussion, we have converted all effect sizes to correlation coefficients (rs)."
 
I haven't seen this type of transform before. My questions are:
 
1. How is it done?
2. Is it a reasonable thing to do?
 
Given my biases on this subject I suspect that it will artificially inflate the effect sizes and make them look as if they were important when they are really trivial but I am willing to be corrected by someone more mathematically knowledgeable than I.
 
As always, your assistance is greatly appreciated.
 
-Don.
 
Don Allen
Psychology Dept.
Langara College
100 W. 49th
Vancouver, B.C. V5Y 2Z6
Canada
604-323-5871
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Mark A. Casteel, Ph.D.
Associate Professor of Psychology
Penn State York
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York, PA  17403
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