About Vivian Expertise I can answer questions on probability, distributions, statistical inference, statistical estimation, hypothesis testing, analysis of categorical data, linear regression, generalized linear regression, ANOVA, and linear mixed models. I cannot answer questions on stochastic processes.
Experience I have worked as a research assistant at the University of Michigan, Ann Arbor for two years.
Organizations American Statistical Association
Education/Credentials University of Michigan, Ann Arbor
Master of Science
Question I have a genetics question: I have three loci (C, P and D), each having 3 possible levels (homo, het, absent). I *think* that gives me 27 possible genotypes for my offspring, but I'd like to say WHY. Is it number of loci to the power of number of levels? What if *one* of the variables only has 2 levels (say, only het or homo)? What if two of them do? Thank you!
Answer Let us only consider the first two loci.
The possible genotypes are
Homo homo
Homo het
Homo absent
(by now, 1*3 types of genotypes)
Het homo
Het het
Het absent
(another 1*3 types of genotypes)
Absent homo
Absent het
Absent absent
(another 1*3 types of genotypes)
Therefore 3*3 types of genotypes for the first two loci.
Similarly 3*3*3 types of genotypes for the three loci.
What if *one* of the variables only has 2 levels?
Then 3*3*2 types of genotypes for the three loci.
Can you see the rule now? What if *two* of the variables only have 2 levels?
3*2*2 types of genotypes for the three loci.
