Nonparametric or distribution-free charts can be useful in statistical process control when there is limited knowledge about the underlying process. In this paper a Shewhart-type chart is considered for the location, based on the Mann-Whitney statistic. The control limit calculations use Lugannani-Rice saddlepoint, Edgeworth and other approximation methods along with Monte Carlo estimation and ...

In CBIR system, relevance feedback is used to improve the retrieval performance. In this paper, a new MannWhitney test based method is presented to identify the features which can distinguish relevant and irrelevant images in a retrieved set. Then the discriminating features are given more emphasis to improve retrieval performance. Proposed scheme is implemented for two different similarity mea...

PURPOSE To determine whether pupil enlargement during phacotrabeculectomy affects postoperative visual acuity and intraocular pressure (IOP) compared to combined surgery without pupil enlargement. METHODS A retrospective study of 74 patients who underwent combined phacotrabeculectomy with (37 eyes) or without (37 eyes) pupil enlargement was performed. Postoperative outcome measures included b...

The nonparametric Wilcoxon–Mann–Whitney test is commonly used by experimental economists for detecting differences in central tendency between two samples. This test is only theoretically appropriate under certain assumptions concerning the population distributions from which the samples are drawn, and is often used in cases where it is unclear whether these assumptions hold, and even when they...

Over a quarter-century ago, Alan Agresti (Biometrics, 1980) proposed using the generalized odds ratio (genOR) to summarize the association between two ordinal variables. Unfortunately, genOR is still largely unknown, even though it is elegantly straightforward and fills key voids in the working statistician’s toolbox. An extension of it, a statistic we are calling “WMWodds,” is an ideal effect-...

Cross entropy and mean squared error are typical cost functions used to optimize classi er performance. The goal of the optimization is usually to achieve the best correct classi cation rate. However, for many two-class real-world problems, the ROC curve is a more meaningful performance measure. We demonstrate that minimizing cross entropy or mean squared error does not necessarily maximize the...

We give an improved algorithm for calculating the exact null distribution of the two sample Mann Whitney Wilcoxon rank sum statistic. The algorithm modifies the update method of Smid using a minimal linked list which directs calculation of only those intermediate probabilities required for the final value. Using an efficient shortened representation of the list of required intermediate values, ...