Question

Chi-Square test question.

Answer 1

When doing the chi test, for expected outcome, do you use phenotype ratio or genotype?

Answer 2

For instance, 500 total children

139 = homozygous
279 = heterozygous
82 = have disease

Their expected was 125:250:125
Means they used 1:2:1 and not 3:1. Kind of confused on this.

Answer 3

u have to use 1:2:1..that is the genotypic ratio. u have not mentioned if dominant or the recessive is the disease character.....but then u have to do like- (1/4)*500 : (2/4)*500 : (1*4) *500...this gives u the expected frequency...while the given data is observed frequency.....here they have given homozygous which might b for both dominant and recessive trait...so u can go about finding the allelic frequency if u r provided with!!

Answer 4

So you use the ratio that closest fits the data??
So if given 297 tall and 93 dwarf, I would use 3:1 assuming classic mendelian?

Answer 5

am confused.,....am really sorry if i ve confused u.....:( for chi square test use ur 3
:1...if u are given with different types of allelic data u ve have to go about in the same way as that of chi square
eg: let SS b dominant
Ss be heterozygous
ss be recessive...here u ll have a degree of freedom 1 and not 2 coz both SS and Ss are dominant....i got confused at this point and so i said to follow 1:2:1
am really sorry abt this mess abb0t.......