Table 3: WCST parameters in schizophrenic and psychotic depression patients (with Bonferroni adaptation applied to statistics and significance level set at 𝑃 < 0 . 0 1 ). No statistical difference shows up.

WCST parameterPatients with schizophrenia ( 𝑛 = 3 0 )Patients with major depression with psychotic features ( 𝑛 = 3 0 )Statistic 𝑈 bitailed

Number of trials 1 1 8 . 4 ± 1 9 . 7 1 2 8 ± 0 2.67 ( 𝑃 > 0 . 0 1 )
% of Errors 4 7 . 2 % ± 1 0 . 7 9 3 4 % ± 1 5 . 2 1.04 ( 𝑃 > 0 . 0 1 )
% of perseverative errors 3 0 % ± 1 1 . 4 1 8 % ± 9 . 9 7 0.01 ( 𝑃 > 0 . 0 1 )
Number of completed categories 3 ± 1 . 3 3 . 8 ± 1 . 6 4 2.09 ( 𝑃 > 0 . 0 1 )
Number of trials to 1st completed category 1 8 . 2 ± 1 2 . 0 8 1 4 . 4 ± 5 . 0 9 1.5 ( 𝑃 > 0 . 0 1 )

* 𝑃 < 0 . 0 1 .
By applying Bonferroni correction with significance level set at ( 𝛼 / 𝑛 = 0 . 0 5 / 5 ), that is, 0.01 instead of 0.05 for each parameter in the whole set, no difference shows up between schizophrenic and psychotically depressed patients regarding the whole set of parameters measured by WCST.