Question

<<Using R exercise>>

Q. Consider the data in anorexia in the MASS library. Find a 98% confidence interval for the variable Prewt and Postwt.

Answer 1

I am writing down the code here which you can run to get the answer.

I have used the following formula for confidence interval from the literature.

#######Following is the code.

confidence=function(data,level)

{

m=mean(data)

s=sd(data)

n=length(data)

t=qt((1-level)/2,df=n-1,lower.tail=FALSE)

lcl=m-(s/sqrt(n))*t

ucl=m+(s/sqrt(n))*t

return(paste("(",lcl,",",ucl,")"))

}

library(MASS)

dat=anorexia

data1=anorexia$Prewt

data2=anorexia$Postwt

conf_lvl=0.98

##Confidence Interval for Prewt

confidence(data=data1,level=conf_lvl)