Mendel's First Law
Variations to Mendel's First Law ChiSquare Test 
The ChiSquare TestAn important question to answer in any genetic experiment is how can we decide if our data fits any of the Mendelian ratios we have discussed. A statistical test that can test out ratios is the ChiSquare or Goodness of Fit test. ChiSquare Formula
Degrees of freedom (df) = n1 where n is the number of classes Let's test the following data to determine if it fits a 9:3:3:1 ratio.
Number of classes (n) = 4 df = n1 + 41 = 3 Chisquare value = 0.47 Enter the ChiSquare table at df = 3 and we see the probability of our chisquare value is greater than 0.90. By statistical convention, we use the 0.05 probability level as our critical value. If the calculated chisquare value is less than the 0 .05 value, we accept the hypothesis. If the value is greater than the value, we reject the hypothesis. Threrefore, because the calculated chisquare value is greater than the we accept the hypothesis that the data fits a 9:3:3:1 ratio.
A ChiSquare Table
Copyright © 2000. Phillip McClean
