Genotype and mating success

Topic: Chi-squared examples · more questions on this topic
‹ Possums in five areas

Fifty mating trials cross genotype (AA, AB, BB) with mating success (no, yes):

	No	Yes
AA	6	6
AB	15	14
BB	2	7

1. Find the expected counts under independence.

2. The Pearson statistic has p-value 0.2853. Is there evidence of an association at level 0.05?

Worked answer (click to show)

Row totals are 12, 29 and 9. Column totals are 23 and 27. The grand total is 50. Expected counts are the products of the margins divided by 50:

	No	Yes
AA	5.52	6.48
AB	13.34	15.66
BB	4.14	4.86

The p-value 0.2853 does not reject independence at level 0.05. These trials do not show an association between genotype and mating success.