Table 2.

Noncentrality Parameters and Powers for Testing for Maternally Mediated Genetic Effects by Using LRTs Based on Either Grandparents, Parents, or a Mother and Her Parents

	χ2 Noncentrality Parameter (Power)b for
		Parental Asymmetry Testd with		Maternal Grandparents Teste with
Scenarioa	Grandparental Asymmetry Testc with 1 df	1 df	2 df	1 df	2 df
1, 1, 1, 1	.0000 (.05)	.0000 (.05)	.0000 (.05)	.0000 (.05)	.0000 (.05)
2, 2, 1, 1	.0000 (.05)	.0000 (.05)	.0000 (.05)	.0103 (.30)	.0104 (.23)
1, 1, 2, 2	.0212 (.54)	.0381 (.79)	.0400 (.72)	.0368 (.77)	.0408 (.73)
1, 1, 3, 3	.0603 (.93)	.1030 (1.00)	.1078 (.99)	.0969 (.99)	.1098 (.99)
1, 1, 2, 4	.0283 (.66)	.0492 (.88)	.0492 (.81)	.0498 (.88)	.0498 (.81)
1, 1, 3, 9	.0859 (.99)	.1375 (1.00)	.1375 (1.00)	.1424 (1.00)	.1424 (1.00)
1, 1, 1, 2	.0003 (.06)	.0006 (.06)	.0027 (.09)	.0006 (.06)	.0040 (.12)
1, 1, 1, 3	.0012 (.08)	.0023 (.10)	.0083 (.19)	.0025 (.11)	.0127 (.28)

^aThe numbers denoting each scenario represent R₁, R₂, S₁, and S₂, respectively.

^bThe χ² noncentrality parameter is found by multiplying the entry in the table by the number of families to be studied. Example powers (for a level-.05 test) are given in parentheses for studies with 200 families. Calculations assumed a stratified population in which half have a baseline risk of .01 and an allele prevalence of .05 and the other half have a baseline risk of .03 and an allele prevalence of .10.

^cTest 1.

^dWilcox et al. 1998.

^eMitchell 1997.