In Section 7.6, you used the finite population correction (fpc) factor to reduce the standard error by a value equal to When developing confidence interval estimates for population parameters, you use the finite population correction factor when samples are selected without replacement from a finite population. If more than 5% of the population is sampled (i.e., ), the finite population correction factor significantly reduces the width of the confidence interval. If less than 5% of the population is sampled, the finite population correction factor has little or no practical effect on the confidence interval width. Equation (8.12) defines the confidence interval estimate for the mean.