huadli
如果服从正态分布的话
可以用SAS中的proc univariate 直接得到参数估计的95%CI
在过程步 中加CIBASIC requests confidence limits for the mean, standard deviation, and variance based on the assumption that the data are normally distributed. For large sample sizes, this assumption is not required for the mean because of the Central Limit Theorem.
如果加 CIPCTLDF requests confidence limits for quantiles by using a method that is distribution-free. In other words, no specific parametric distribution such as the normal is assumed for the data. PROC UNIVARIATE uses order statistics (ranks) to compute the confidence limits as described by Hahn and Meeker (1991). 也就是可以得到median的95%CI