gggg Q 5 The genotype of an individual at a given position i

Q. 5 The genotype of an individual at a given position in the genome (called a locus) can be coded as a categorical variable with three levels usuly labelled AA, Aa and aa. A study was conducted looking at how the genotype at one specific locus affects systolic blood pressure. Here is the output from PROC GLM The GLM Procedure Dependent Variable: sb Sum of Source Model Error Corrected Total DF 4 25 29 Squares Mean Sqre F Value Pr> F 8.31 0.0002 613.679849 461.786818 1075.466667 153.419962 18.471473 Source gender age gene Type III SS 269.2466292 169.8072899 167.3908980 Mean Squar Value 269.2466292 169.8072899 DF Pr>F 14.58 0.0008 9.19 0.0056 4.53 0.0209 83.6954490 https://www.coursehero.com/file 7410508/S3A03exam2011/ Continued on Page 4

Solution

To fit different slopes for males and females for the age variable, we can make two different groups for males and females.

Then the regression test can be run on the smaller samples of k and n-k respectively.

thus a different slope for age can be obtained.

To test whether or not two different models / slopes were needed or not we can check if the coefficients obtained are statistically same or not.

If they turn out to be statistically same and each of them is same to the one with the combined model as well, then we can have a single model or a single value of slope for the age variable for both males and females else we can not.

Hope this helps.