Please help!! How do I CALCULATE the expected value? Chi square test!!Watch
An experiment was carried out to investigate the inheritance of grain shapes and colour in maize. The number of each type of grain on a cob were counted (observed number).
The results are shown in the table below:
it was predicted that the phenotype would be in the ratio 9 : 3 : 3: 1 and a chi-squared test was used to investigate whether there was a significant difference between the observed results and the expected results.
Complete the table by calculating the expected number (E) of grains of each phenotype.
So what I did was:
the ratio is 9 : 3 : 3 : 1
For yellow & smooth: 9/16 x 53 = 29.8125
Yellow & wrinkled: 3/16 x 20 = 3.75
and so on ...
but my answers are all wrong?? Where did I go wrong and what's the correct way to calculate the expected value?
But you want to multiply the expected ratio (i.e. 9/16) by the TOTAL count (53 + 20 + 17 + 10 = 100)
So they should be:
yellow/smooth: 9/16 * 100 = 56.25
yellow/wrinkled: 3/16 * 100 = 18.75
white/smooth: 3/16 * 100 = 18.75
white/wrinkled: 1/16 * 100 = 6.25
You can see that these are much closer to the observed values.
I'm sure you can fill out the last column yourself from that