Nothing
relative.risk<-function(A=NULL,show.matrix=FALSE,conf.int=FALSE,level=0.05){ #IC for n large
c1<-is.matrix(A)
if(!c1){
A<-input2()
}else{
c2<-nrow(A)==2
c3<-ncol(A)==2
if(!c2|!c3){A<-input2()}
}
c4<-any(apply(A,2,sum)==0)
while(c4){
message("Sum of rows can not be zero",'\n')
A<-input2()
c4<-any(apply(A,2,sum)==0)
}
message("Relative risk for a 2x2 contingency table",'\n')
if(show.matrix==TRUE){
rownames(A)<-c("Presence","Absence")
colnames(A)<-c("Disease","Without disease")
print(A)
}
R1=A[1,1]/(A[1,1]+A[1,2])
R2=A[2,1]/(A[2,1]+A[2,2])
RR=R1/R2
if(conf.int==TRUE){
while((level>=1)|(level<=0)){
message("Level of the confidence interval is a value between 0 and 1",'\n')
level<-as.numeric(readline("What is the value of the level?\n"))
}
LI<-qnorm(level/2)*sqrt((1-R1)/(sum(A[1,])*R1)+(1-R2)/(sum(A[2,])*R2))
CI<-sort(exp(c(log(RR)-LI, log(RR)+LI)))
L<-list(RR,CI);names(L)=c("Relative Risk",paste("Confidence Interval of level ",level*100,"%",sep=""))
return(L)
}else{
return(RR)
}
}
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