Table 4.

Split-half reliability of the Gibson Test of Cognitive Skills

Test	Age (years)						Overall
	6–8	9–12	13–18	19–30	31–54	55+
Long-term memory	0.95	0.94	0.95	0.93	0.94	0.95	0.95
Short-term memory	0.90	0.84	0.86	0.92	0.84	0.83	0.90
Visual processing	0.97	0.98	0.98	0.98	0.99	0.99	0.99
Auditory processing	0.97	0.97	0.96	0.97	0.96	0.96	0.97
Logic and reasoning	0.90	0.86	0.86	0.80	0.81	0.86	0.90
Processing speeda	0.88	0.81	0.87	0.88	0.88	0.91	0.89
Word attack	0.94	0.94	0.90	0.89	0.90	0.85	0.94

Note:

^aSplit-half correlation is not an appropriate analysis for a speeded test; the alternative calculation was based on the formula: r₁₁=1− (SEM²/SD²).

Abbreviations: r, reliability; SD, standard deviation; SEM, standard error of measurement.