For each SNP the Cochrane-Armitage trend-test statistic is computed
from a 3x2 contingency table

Cases | Controls | Row totals | |

AA | |||

AB | |||

BB | |||

Column totals |

() and () and () are the total number of occurrences of genotype AA, AB and BB, respectively, for the cases (controls), and

The Cochrane-Armitage trend-test statistic with weights is defined as

The MAX statistics is equal to the maximum of the three Cochrane-Armitage trend-test statistic obtained when assuming a recessive ( ) model, a dominant model ( ) and an additive model ( ). When assuming an additive model( ), the Cochrane-Armitage trend-test statistic is equal to

where , and .

Marit Holden 2008-08-07