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arXiv 0711.3236stat.ME
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利用先验信息回归的置信区间

Confidence intervals in regression utilizing prior information

Paul Kabaila, Khageswor Giri

摘要:

考虑一个线性回归模型,回归参数β =(beta_1,.,beta_p)和独立同分布的误差N(0,sigma^2)。假设感兴趣的参数是theta = a^T beta,其中a是指定的向量。定义参数tau=c^T beta-t,其中向量c和数t被指定,并且a和c线性独立。还假设我们有不确定的先验信息tau = 0。我们提出了一个新的频率1-α置信区间θ,利用这一先验信息。我们要求该置信区间(a)具有数据的连续函数的端点,以及(b)当数据与该先验信息强烈矛盾时,与标准1-alpha置信区间一致。这个区间是最优的,因为它具有最小加权平均预期长度,其中当tau=0时,最大权重被赋予这个预期长度。这种最小化导致具有以下期望性质的间隔。该间隔具有预期长度,该预期长度(a)在关于tau的先验信息正确时相对较小,并且(b)具有不太大的最大值。下面的问题将被用来说明这个新的置信区间的应用。考虑20次重复的2 x 2析因实验。假设感兴趣的参数θ是一个指定的简单效应,并且我们有两因子交互作用为零的不确定先验信息。我们的目标是找到一个频率论的0.95置信区间θ,利用这种先验信息。

英文摘要:

We consider a linear regression model with regression parameter beta=(beta_1,...,beta_p) and independent and identically N(0,sigma^2) distributed errors. Suppose that the parameter of interest is theta = a^T beta where a is a specified vector. Define the parameter tau=c^T beta-t where the vector c and the number t are specified and a and c are linearly independent. Also suppose that we have uncertain prior information that tau = 0. We present a new frequentist 1-alpha confidence interval for theta that utilizes this prior information. We require this confidence interval to (a) have endpoints that are continuous functions of the data and (b) coincide with the standard 1-alpha confidence interval when the data strongly contradicts this prior information. This interval is optimal in the sense that it has minimum weighted average expected length where the largest weight is given to this expected length when tau=0. This minimization leads to an interval that has the following desirable properties. This interval has expected length that (a) is relatively small when the prior information about tau is correct and (b) has a maximum value that is not too large. The following problem will be used to illustrate the application of this new confidence interval. Consider a 2-by 2 factorial experiment with 20 replicates. Suppose that the parameter of interest theta is a specified simple effect and that we have uncertain prior information that the two-factor interaction is zero. Our aim is to find a frequentist 0.95 confidence interval for theta that utilizes this prior information.

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