The psychopathology of everyday art: a quantitative Study - World ...

attention to overall effect sizes than the difference between individual studies 229 . The
complex issue of which set of statistics to use is largely a matter of judging the structure
of the data and applying as fair a method as possible 230 . This problem was dealt with
empirically by coding the characteristics for each study and comparing the different
partitions of the variables 231 as tabulated in the qualitative analysis.
Tables were prepared using 2 techniques:
(1) all variables were included to produce a single aggregated case for each
experimental group in the analysis;
(2) the identified tabulated areas were compared on effect size and subsets of the
most significant tables, which retained all studies in the analysis were aggregated
for each type of control group;
Other criticisms focus on interaction effects, of which 2 are taken into account in this
analysis; small sample sizes and weighting for size of study 232 .
There were 4 questions to be answered:
Is the art-test a discriminable dimension for psychiatric diagnosis for (1) patients
from non-patients; and (2) within patient groups.
229
David Healy (1998), Commentary: meta analysis of trails comparing anti-depressants with active
placebos, British J. Psychiatry , V.17:232-4; David Sohn (1997), Questions for meta analysis,
Psychological Reports , V.81(1):3-15.
230
R. Rosenthal (1998) Meta analysis: concepts, corollaries and controversies, in J.G. Adair and D.
Bellanger (eds.) Advances in Psychological Science , V.1:371-384.
231
Rosenthal (1984) op.cit; Wolf (1986) op.cit. and using procedures for calculation from Carol Taylor
Fitzgibbon and Lynn Lyons Morris (1987), How to Analyse Data , Beverley Hills, CA: Sage, Chapter 7.
Meta Analysis pp.132-145.
232 The major criticism of bias in meta analyses of treatment methods, Wolf (1986) op.cit.
174