SCRIPT TO APPLY ASSIGNMENT 3 FUNCTIONS TO THE SUPPLIED DATA.
Read the function definitions.
> source("http://www.cs.utoronto.ca/~radford/csc120/a3funs.r")
Read the data, and compute the BMD_change variable as the change in BMD from beginning of experiment to end.
> df <- read.table("http://www.cs.utoronto.ca/~radford/csc120/a3data",header=TRUE)
> df$BMD_change <- df$BMD2 - df$BMD1
Specify which variables we want to look at effects for.
> vars <- c("BMD2","BMD_change","headache", "stomachache")
Set the random number seed so that we can reproduce results.
> set.seed(1)
Find effects and p-values for all subjects.
> print_effects_with_pvalues(df,vars)
BMD2 BMD_change headache stomachache
effect 10.964 14.732 -0.001828 0.017796
pvalue 0.076 0.000 0.764000 0.000000
Number of subjects: 500
Find effects and p-values for male subjects.
> print_effects_with_pvalues(df[df$sex=="M",],vars)
BMD2 BMD_change headache stomachache
effect -5.394155 7.368258 -0.004020432 0.01495676
pvalue 0.667000 0.097000 0.788000000 0.01800000
Number of subjects: 130
Find effects and p-values for female subjects.
> print_effects_with_pvalues(df[df$sex=="F",],vars)
BMD2 BMD_change headache stomachache
effect 15.27578 17.26616 -0.001304774 0.01882394
pvalue 0.06300 0.00000 0.671000000 0.00000000
Number of subjects: 370
Find effects and p-values for female subjects less than age 50.
> print_effects_with_pvalues(df[df$sex=="F" & df$age<50,],vars)
BMD2 BMD_change headache stomachache
effect -6.355556 5.613675 -0.002598291 0.01426496
pvalue 0.666000 0.232000 0.718000000 0.02900000
Number of subjects: 84
Find effects and p-values for female subjects age 50 or above.
> print_effects_with_pvalues(df[df$sex=="F" & df$age>=50,],vars)
BMD2 BMD_change headache stomachache
effect 22.46714 20.4195 -0.000870403 0.02004441
pvalue 0.01900 0.0000 0.581000000 0.00000000
Number of subjects: 286