Document Type: Regular Paper
Department of Mathematics, Statistics and Physics, Qatar University, Doha, Qatar Department of Mathematical Sciences, Isfahan University of Technology, Isfahan, I. R. of Iran
3RTI International, Research Triangle Park, North Carolina, USA
School of Mathematics and Statistics, Carleton University, Ottawa, Canada
We develop a two phase sampling procedure to determine the sample size necessary to estimate
the population mean of a normally distributed random variable and show that the resulting estimator has preassigned variance and is unbiased under a regular condition. We present a necessary and sufficient condition under which the final sample mean is an unbiased estimator for the population mean.