Maximum pseudo-likelihood (MPL) is a semiparametric estimation method often used to obtain the dependence parameters in copula models from data. It has been shown that despite being consistent, and in some cases efficient, MPL estimation can overestimate the level of dependence especially for small weakly dependent samples. We show that the MPL method uses the expected value of order statistics and we propose to use instead the median or the mode of the same order statistics. In a simulation study we compare the finite-sample performance of the proposed estimators with that of the original MPL and the inversion method estimators based on Kendall's tau and Spearman's rho. Our results indicate that the modified MPL estimators, especially the one based on the mode of the order statistics, have better finite-sample performance, while still enjoying the large-sample properties of the original MPL method.
翻译:最大假象(MPL)是一种半参数估计方法,通常用来从数据中获得相交模型的依赖参数。它表明,尽管这种估计是一致的,而且在某些情况下是有效的,但MPL估计可以高估依赖程度,特别是对于小的依赖性弱的样本。我们表明,MPL方法使用定序统计的预期值,我们提议用中位值或相同定序统计的模式替代中位值或同一定序统计的模式。在模拟研究中,我们比较了拟议定位数的有限抽样性能与最初的MPL和基于Kendall's Tau 和Spearman rho 的定流方法的估测者。我们的结果显示,修改的MPL估计者,特别是以定序统计模式为基础的估计者,在仍然享受原MPL方法的大样特性的同时,具有更好的定位抽样性性能。