本文是探討F分配的最小信賴區間。Crisman在1975年的論文提到可利用二分法來尋找Chi-Square分配的最小信賴區間之臨界值。本篇論文會先探討Crisman的研究,並使用相同的方法探討F分配的最小信賴區間之臨界值,最後提供範例與SAS Macro程式供讀者使用。 This article is to explore the minimum length of confidence interval of F distribution. In 1975, Crisman had mentioned a bisection method to calculate the confidence interval with the minimum length about the Chi-Square distribution to meet the desired critical values. This paper will first explore Crisman’s research and applies the same method on F distribution to find the confidence interval with minimum length, finally we will provide a SAS Macro program and use some examples to illustrate how to use it.