如何消去煩擾參數是一個統計推論中重要的問題，利用輔助統計量的條件分佈是方法之一。關對「輔助」(ancillarity) 這一概念，Andersen (1970)和Basawa (1981)，曾分別提出不同的定義，Liang (1983) 証明，若考慮的分佈屬於指數函數族，當二定義等價。本文主要工作是指出該二定義等價之充分條件，該條件涵蓋至廣，指數函數族僅為其中一例；文末並討論它們與「F-訊息」間之關係。

Eliminating nuisance parameters from the likelihood function so that inference can be made about the parameters of interest is an important problem in statistics. Conditioning on an ancillary statistic is ol1e of the methods of parametric reduction. Andersen (1970)and Basawa (1981) suggested different conceptsof ancillarity. Liang (1983) showed that they are equivalent for exponential families of distributions. This paper investigates relationship between them in general situation. The relation to F -information is also discussed.