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

than the stepwise option at correctly classifying the subjects but there is a clearer
indication of the extent to which particular variables contribute to the discrimination
process.
It was necessary to control for uneven numbers between groups as the patient
group was nearly four times the size of the control group, otherwise there wouldn't be
an even chance of allocation to either group. The PRIORS subcommand within the SPSS
program adjusts the calculation for the sizes of the groups according to the prior
probability of chance allocation to one group or another. Prior probability was thus set
to 75/25%.
Subordinate analyses
Correlations between DAPA variables
For exploratory analysis, the Pearson Product Moment Correlation (Pearson's r) is the
most commonly used measure of linear association between continuous variables. Bi-
variate scatter plots for the significant variables were generated to check the distribution
of the data because there are restrictions on the validity of the associated hypotheses
tests. The significance of the correlation coefficient is valid for random samples with at
least one normally distributed variable. 2 tailed tests were used because, although
hypotheses were made, there was little scientific reason to expect that correlations would
be in any particular direction.
Correlation is often used as exploratory analysis, but even with only a dozen
variables here, 66 r values are produced. 5 populations are tested, thus 1 value in 20 will
be significant at the 5% level purely by chance! This level of analysis was rather too
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