The proportions of blood types O, A, B, and AB in the general population of a particular country are known to be in the ratio 49
:38:9:4, respectively. A research team, investigating a small isolated community in the country, obtained the following frequencies (i.e. observed number of cases) of blood type. Blood type O A B AB
Frequency 87 59 20 4
Test the hypothesis that the proportions in this community do not differ significantly from those in the general population.
The critical region is <u>χ</u>²≥ χ²(0.05,3) = 7.82 for alpha = 0.05 and
<u>χ</u>²≥ χ²(0.01,3) = 11.34 for alpha = 0.01
As the calculated value lies in the critical region for both value of alpha we reject our null hypothesis and accept our alternate hypothesis. The proportions differ significantly from those in the general population.