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.

Table 7: Calculating chi-square value.


Observed (O) Expected (E) Deviation (O-E) (O-E)2

(O-E)2/ E

A (OH88119)

85 49.25 35.75 1278.0625


B (6.8068)

46 49.25 -3.25 10.5625


H (heterozygous)

66 98.50 -32.50 1056.25


        XSUM =


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.