The expected result under the null hypothesis of equal proportions for the four genotypes AaBb, Aabb, aaBb, and aabb would be: 300 offspring (total number of offspring / 4)
The result under the null hypothesis of equal proportions for the four genotypes AaBb, Aabb, aaBb, and aabb would be:
300 offspring (total number of offspring / 4)
Therefore, the expected number of offspring for each genotype would be:
AaBb: 300 (expected total) * 1/4 = 75
Aabb: 300 (expected total) * 1/4 = 75
aaBb: 300 (expected total) * 1/4 = 75
aabb: 300 (expected total) * 1/4 = 75
To determine if the observed results (300 AaBb, 300 aabb, 200 Aabb, and 200 aaBb) deviate significantly from the expected results under the null hypothesis, we can perform a chi-square test.
Here's how to calculate the chi-square statistic:
Calculate the squared deviations from expectation for each genotype:
AaBb: ((300 observed - 75 expected) ^ 2) / 75 expected = 425
Aabb: ((300 observed - 75 expected) ^ 2) / 75 expected = 425
Aabb: ((200 observed - 75 expected) ^ 2) / 75 expected = 169
aaBb: ((200 observed - 75 expected) ^ 2) / 75 expected = 169
Sum the squared deviations from expectation:
425 + 425 + 169 + 169 = 1188
This is the chi-square statistic.
With a chi-square statistic of 1188, we can compare it to a chi-square distribution table with 3 degrees of freedom (number of categories - 1) at a chosen significance level (e.g., alpha = 0.05).