Table Table 2.

A 2 × 2 table constructed from data reported by McCracken et al. 56 on the association between allelic variants of rs1800544 in the adrenergic α2A receptor gene and clinical response to methylphenidate in autism spectrum disorder with comorbid hyperactivity ( P  < 0.02), from which the corresponding values for sensitivity, specificity, PPV, and NPV have been calculated

	Responder	Nonresponder
ADRA2 rs1800544 G allele present (G/G or G/C)	12	18	30
ADRA2 rs1800544 G allele absent (C/C)	20	8	28
	32	26	58

ADRA2, adrenergic α2A receptor gene; NPV, negative predictive value; PPV, positive predictive value.

Sensitivity: 12/32 = 37.5%.

Specificity: 8/26 = 30.8%.

PPV: 12/30 = 40.0%.

NPV: 8/28 = 28.6%.