library(survey)
source("c:/courses/st446/rcode/confintt.r")
# In Excel, save your spreadsheet as a text tab-delimited file
# If variable names are in row 1, then use  header=T)

ratio <- read.table("c://courses/st446/Rcode/agsrs.txt",header=T)

N=3078        # population size
n=300         # sample size

tx=964470625                 # X population total if known
mux = tx/N                   # X population mean  if known
ratio_ttl  <- tx*ratio$ACRES92      
ratio_mn   <- ratio_ttl/N 

mnhatx  = mean(ratio$ACRES87)  # estimated X population mean  if unknown
thatx = N*mnhatx              # estimated X population total if unknown
ratio_umn  = mnhatx*ratio$ACRES92
ratio_uttl = N*ratio_umn
fpc <- c(rep(N,n))

ratio <- cbind(ratio,fpc,ratio_ttl,ratio_mn,ratio_uttl,ratio_umn)
ratio <- data.frame(ratio)

# Create the sampling design
  agdsgn <- svydesign(data=ratio,id=~1,fpc=~fpc)

# Estimation of the ratio

agratio <- svyratio(~ACRES92,~ACRES87,design=agdsgn)
confint.t(agratio,tdf=n-1,level=.95)

# Estimation of the y population mean (when tx is known)

agratio_mean <- svyratio(~ratio_mn,~ACRES87,design=agdsgn)
confint.t(agratio_mean,tdf=n-1,level=.95)

# Estimation of the y population total (when tx is known)

agratio_total <- svyratio(~ratio_ttl,~ACRES87,design=agdsgn)
confint.t(agratio_total,tdf=n-1,level=.95)

# Estimation of the y population mean (when tx is unknown)

agratio_umean <- svyratio(~ratio_umn,~ACRES87,design=agdsgn)
confint.t(agratio_umean,tdf=n-1,level=.95)

# Estimation of the y population total (when tx is unknown)

agratio_utotal <- svyratio(~ratio_uttl,~ACRES87,design=agdsgn)
confint.t(agratio_utotal,tdf=n-1,level=.95)