Genotyping Example, Step 4 - Plugging Numbers Into The Formula
Now we are ready to work with the entire chi-square formula.
Remember that the formula for calculating the X2 value is:
X2 = Σ (observed – expected)2/ expected
Once again we continue to expand our chi-square calculation table and determine a final chi-square value for our experimental data.
|
Class |
Observed (O) | Expected (E) | Deviation (O-E) | (O-E)2 |
(O-E)2/ E |
|
A (OH88119) |
85 | 49.25 | 35.75 | 1278.0625 |
25.9505 |
|
B (6.8068) |
46 | 49.25 | -3.25 | 10.5625 |
0.2145 |
|
H (heterozygous) |
66 | 98.50 | -32.50 | 1056.25 |
10.7234 |
| X2 SUM = |
36.8884 |
The next page of this lesson has a video tutorial showing in more detail how these numbers are calculated, as well as how to interpret the final chi-square value. We will need to determine if we will need to reject or "fail to reject" our hypothesis of the co-dominant inheritance pattern of CosOH57 in our specific tomato population.