ABSTRACT
Comparing single means: Consider the case of comparing the value of a single variable between two groups of subjects. For example, one may measure the blood level of a protein that is suspected to be elevated in patients with a certain type of cancer. e mean levels the protein in the two groups may be compared to determine if they are signicantly dierent by employing a t-test. In another case, the frequencies of an SNP in two dierent groups may be compared to determine if they are signicantly dierent. Fisher’s exact test or a chi-squared test may be used in this case. In both of these examples, there is a single variable being measured-a real number in the rst case and a Boolean variable (YES = suspected SNP variant is present; NO = suspected SNP variant is absent) in the second in several observations (number of subjects).
