The Effect of Sample Size

Enter number of progeny:   
Genotypes Phenotypic Ratios
  RS Rs rS rs Chi2 p0.05
RS RRSS
RRSs
RrSS
RrSs
purple
starchy
Rs RRSs
RRss
RrSs
Rrss
yellow
starchy
rS RrSS
RrSs
rrSS
rrSs
purple
sweet
rs RrSs
Rrss
rrSs
rrss
yellow
sweet

If you were to count 16 kernels on an ear of dihybrid F2 corn, you would not be likely to find nine purple starchy kernels, three purple sweet kernels, three yellow starchy kernels, and one yellow sweet kernel. But if you counted a thousand, you would not be surprised to find that the observed ratio was very close to the expected one.

In the table above, you may choose the sample size (up to 99,999, which may take a while to calculate), and the program will generate gametes, fill in the Punnett square, and calculate the phenotypic ratios. It will also calculate the chi-squared statistic, to show that most observed ratios are not significantly different from the expected.


jcclark@csupomona.edu
© 2001 by Curtis Clark