srsratio.n=function(data,N,s2r,mux,taux,param,B){
  data=as.name(data); param=as.name(param)
  mux=mux; taux=taux; N=N; s2r=s2r; B=B
  if(param=='ratio'){
    D=(B^2*mux^2)/4
  }    else if(param=='mean'){  
    D=B^2/4
  }      else if(param=='total'){  
    D=B^2/(N^2*4)
  } 
  n=ceiling((N*s2r)/(N*D+s2r))
  cat("","\n","Sample size estimation for SRS data ",data,"\n","Ratio estimation for ",param,"\n","N =",N,
      "Required bound =",B,'\n',"Estimated variance =",s2r,"\n","Mean of x (mu.x) =",mux,"\n","Total of x (taux) =",taux,"\n","Estimated sample size =",n,"\n")
  results=list(data=data,N=N,s2r=s2r,mux=mux,taux=taux,B=B,D=D,n=n)
}
# to use the function with its call: 
# srsratio.n(data,N,s2r,mux,taux,param,B)
# data: name of dataset, in quotes
# N: population size
# s2r: variance=sum(y-rx)^2/(n-1)
# mux: true mean of X or xbar
# taux: true total of X, N*mux, or N*xbar
# param: c('ratio','mean','total')
# B: desired bound