Let's test the following data to determine if it fits a 9:3:3:1 ratio.
|
315 Round, Yellow Seed |
|
108 Round, Green Seed |
|
101 Wrinkled, Yellow Seed |
|
32 Wrinkled, Green |
|
556 total seeds |
Expected Values:
(9/16)(556) = 312.75 Round, Yellow Seed
(3/16)(556) = 104.25 Round, Green Seed
(3/16)(556) = 104.25 Wrinkled, Yellow
(1/16)(556) = 34.75 Wrinkled, Green
number of classes (n) = 4; df = n-1 = 4-1 = 3
Enter the Chi-Square table at df = 3 and we see our chi-square value fall between 80% and 95%. Thus we accept the hypothesis that two independent genes are controlling the two traits.
