diff --git a/lab10.R b/lab10.R new file mode 100644 index 0000000..bedd059 --- /dev/null +++ b/lab10.R @@ -0,0 +1,115 @@ +library(mosaicData) +library(MASS) + +# Q1 +set.seed(123) + +truemean=mean(TenMileRace$net) + +lowerbounds=rep(0, 20) +upperbounds=rep(0, 20) +containsmean=rep(FALSE, 20) + +for(i in 1:20) +{ + racetimes25=TenMileRace$net[sample(1:nrow(TenMileRace), 25)] + + raceci=t.test(racetimes25) + + lowerbounds[i]=raceci$conf.int[1] + upperbounds[i]=raceci$conf.int[2] + containsmean[i]=truemean >= lowerbounds[i] & truemean <= upperbounds[i] +} + +ciresults=data.frame( + sample=1:20, + lower=lowerbounds, + upper=upperbounds, + containstruemean=containsmean +) + +ciresults +sum(containsmean) + +# Q2 +femalecats=subset(cats, Sex=="F") +malecats=subset(cats, Sex=="M") + +femalebodyci=t.test(femalecats$Bwt) +femaleheartci=t.test(femalecats$Hwt) +malebodyci=t.test(malecats$Bwt) +maleheartci=t.test(malecats$Hwt) + +femalebodyci +femaleheartci +malebodyci +maleheartci + +# Q3 +set.seed(123) + +racetimes30=TenMileRace$net[sample(1:nrow(TenMileRace), 30)] +racetimes230=TenMileRace$net[sample(1:nrow(TenMileRace), 230)] +racetimes430=TenMileRace$net[sample(1:nrow(TenMileRace), 430)] + +ci30=t.test(racetimes30) +ci230=t.test(racetimes230) +ci430=t.test(racetimes430) + +ci30 +ci230 +ci430 + +ci30$conf.int +ci230$conf.int +ci430$conf.int + +# Q4 +confidence=function(data, conflevel) +{ + ci=t.test(data, conf.level=conflevel) + + lowerbound=ci$conf.int[1] + upperbound=ci$conf.int[2] + confpercent=attr(ci$conf.int, "conf.level") * 100 + + cat("We are", confpercent, + "percent sure that the mean is between", + lowerbound, "and", upperbound, ".") +} + +confidence(survey$Age, 0.99) + +# Q5 +confidence=function(data, conflevel, meaninfo, units) +{ + CI=t.test(data, conf.level=conflevel) + + lowerbound=CI$conf.int[1] + upperbound=CI$conf.int[2] + confpercent=attr(CI$conf.int, "conf.level") * 100 + + cat("We are", confpercent, "percent sure that the mean", + meaninfo, "is between", lowerbound, "and", upperbound, + units, ".") +} + +confidence(survey$Age, 0.99, "student age", "years") + +# Q6 +confidence=function(data, conflevel=0.95, meaninfo, units) +{ + CI=t.test(data, conf.level=conflevel) + + lowerbound=CI$conf.int[1] + upperbound=CI$conf.int[2] + confpercent=attr(CI$conf.int, "conf.level") * 100 + + cat("We are", confpercent, "percent sure that the mean", + meaninfo, "is between", lowerbound, "and", upperbound, + units, ".") +} + +confidence(survey$Age, 0.90, "student age", "years") +confidence(survey$Age, 0.95, "student age", "years") +confidence(survey$Age, quantity="student age", units="years") \ No newline at end of file