Share
Explore BrainMass

Chi-squared test for HW equilibrium

The MN blood group in humans is under the control of a pair of codominant alleles, LM
and LN. In a group of 556 individuals, the following genotypic frequencies are found:

167 MM
280 MN
109 NN

(a) Calculate the frequency of the LM and LN alleles.

(b) Test (using the Chi-squared test) whether the genotype frequencies conform to the
Hardy-Weinberg distribution.
Genotypes
MM MN NN Sum
Observed number
Observed frequency
Expect frequency
Expected number
(O-E)2/E

Solution Preview

1. MM=p2=167/556=.30
MN=2pq=280/556=.50Next
NN=q2=109/556=.20

First determine the frequency of M using the following equation: p2+1/2(2pq). Substitute the numbers from each of the above observed values and solve for p.
.30=1/2(.50) =.55 therefore P=.55
1-.55=.45
To get pq simply multiply the above values. To get 2 pq multiply pq by 2.
pq= .55x.45=.2475
2pq=.2475x2=.495
p2=.3025
q2=.2025

These solutions are the expected frequencies for the alleles if the population ...

Solution Summary

This solution will explain how to use a chi-squared test to determine whether or not the blood groups of a population are in Hardy-Weinberg equilibrium. A link to a similiar example problem is included.

$2.19