Table 2. Descriptive analysis of executive functioning scores for the schizophrenia (n=141) and control groups (n=119) after correction using analysis of covariance (ANCOVA) with non-verbal intelligence quotient as a covariant, as well as the internal reliability of cognitive tasks, which that was entered in the confirmatory factor analysis.

	Schizophrenia patients			Healthy controls
Tasks	Mean (SD)	Skewness*	Kurtosis*	Mean (SD)	Skewness*	Kurtosis*	df	F	p-value	Reliability
Visual working memory	5.9 (3.96)	0.16	-1.07	8.95 (4.49)	-0.18	-0.79	1.256	33.170	< 0.001	0.77†
Keep track	114.50 (26.43)	-0.03	-0.31	130.96 (18.17)	-0.43	-0.14	1.256	24.109	< 0.001	0.76‡
Letter memory	13.16 (3.83)	-0.55	-0.39	16.81 (3.16)	-1.09	-0.99	1.256	31.523	< 0.001	0.92†
Stroop§	0.67 (0.41)	0.81	0.07	0.42 (0.18)	0.79	0.87	1.256	34.080	< 0.001	0.70‡
Semantic generation§	2.19 (0.92)	-0.05	-0.05	1.67 (0.92)	-0.14	-0.88	1.256	18.344	< 0.001	0.86‡
Plus-minus§	41.33 (29.41)	-0.07	-0.83	22.45 (17.05)	0.22	-1.05	1.256	38.319	< 0.001	0.81‡
Number-letter§	32.59 (20.42)	0.24	-0.78	17.19 (8.83)	0.47	0.14	1.256	56.410	< 0.001	0.84‡
Trial making§	47.11 (31.45)	0.66	-0.41	33.07 (15.58)	0.49	-0.62	1.256	38.499	< 0.001

df = degrees of freedom; SD = standard deviation.

^*Skewness and Kurtosis after root square transformations.

^†Reliability was calculated using Cronbach’s alpha.

^‡Reliability was calculated by adjusting split-half correlations with the Spearman-Brown prophecy formula.

^§Measured as response/interference time.