George S. Easton

The 1993 State of U.S. Total Quality Management: A Baldrige Examiner's Perspective

This article assesses the current state of U.S. total quality management based on the authors experience evaluating 22 companies as an Examiner for the Malcolm Baldrige National Quality Award during the last four years. The companies that apply for the award have many important strengths and these are yielding substantial improvement in customer satisfaction, employee involvement, and operational results. They also, however, have many identifiable areas which need improvement. A number of factors are limiting the development of truly comprehensive and fully integrated quality management systems.

General Saddlepoint Approximations with Applications to L Statistics

Abstract Saddlepoint approximations are extended to general statistics. The technique is applied to derive approximations to the density of linear combinations of order statistics, including trimmed means. A comparison with exact results shows the accuracy of these approximations even in very small sample sizes.

A Multivariate Generalization of Quantile-Quantile Plots

Abstract In this article we present a multivariate generalization of quantile-quantile (Q-Q) plots. Like univariate Q-Q plots, these plots are useful for examining the distributional shape of multivariate point clouds. These plots are based on finding a matching between the points of the data set whose shape is being examined and a reference sample. Graphical displays of how well the point clouds match are then developed. The reference sample used as the basis for comparison is typically derived from a random sample from a known multivariate distribution. The approach presented in this article is both a direct extension of the usual univariate Q-Q plot and truly multivariate in nature. It is truly multivariate in that the displays we develop show different aspects of one multivariate comparison between the data and the reference sample. This is unlike most generalizations of Q-Q plots to the multivariate case, which are based on making standard univariate Q-Q plots after some function of the multivariate ...

Micro- and macrokinetic behavior of the subunit gating channel

SummaryThe concept of a channel that builds up from subunit molecules by way of aggregation can provide the framework for a unified description of electrical excitability in cell and model membranes at the micro- and macrokinetic level. Monte Carlo simulations of the microkinetics of a subunit channel predict two extreme kinds of gating behavior. Depending on the reaction parameters, a simulation can result either in single-step open-closed microkinetics, as elucuidated by noise analysis of excitable cell membranes, or in records resembling the multi-step conductance bursts that are measured in lipid bilayers modified by alamethicin. Numerical calculations of the voltage-clamp macrokinetics for the two cases reveal that the set of parameters that produces nerve- and muscle-like fluctuations gives Hodgkin-Huxley-type time courses, while the set that results in alamethicin-like fluctuation behavior gives alamethicin-like macrokinetics. The macrokinetic behavior is generated by summing microkinetic simulations for the nerve and the alamethicin case.

Compromise maximum likelihood estimators for location

Abstract This article describes a new approach for constructing robust location estimators. These estimators are constructed to be nearly optimal in small sample sizes simultaneously for two or more possible underlying shapes of the density of the data. The estimators are weighted averages of the maximum likelihood estimators for the densities considered, where the weights depend on the sample through the likelihood functions. Because of this relationship to the usual MLEs, these estimators are called compromise maximum likelihood estimators (CMLEs). For the CMLEs to exhibit good robustness properties, the densities used to construct the CMLEs should be chosen to, in a sense, “span” a reasonable range of possible underlying distributions of the data encountered in practice. For example, to construct CMLEs with the usual robustness properties, that is, which perform well both for narrow-tailed Gaussian data and for data containing outliers or from wide-tailed distributions, the CMLEs might be constru...

Markov process characterization of a single membrane gating site

Abstract We present a method by which the expected macroscopic kinetic behavior of a membrane patch containing many independent gating sites can be determined analytically from a Markov formulation of the probabilistic nature of a single gating site. This method is applicable to any kinetic system with a small number of reactants and subject to the principle of detailed balance. Using this method calculations are carried out based on the concept of aggregation gating involving a voltage-dependent reversible first-order reaction followed by a voltage-independent reversible aggregation process taking place within the microscopic area of the gating site. The basic macrokinetic properties of the potassium and sodium conductance system are derived from a hypothetical aggregation gating site consisting of four molecules. These results are quantitatively consistent with the average of a large number of individual sample paths generated by Monte Carlo simulations for the same model and the same parameters.

A Simple Dynamic Graphical Diagnostic Method for Almost Any Model

Abstract This article describes a simple dynamic graphical diagnostic method that can be used to explore fits to almost any parametric model. The technique is based on viewing diagnostic plots while fits in a neighborhood of a parametric fit are dynamically explored using an intuitively appealing and easy-to-use two-dimensional controller. The motivation for the controller comes from the 2 p -factorial designs used in response surface analysis. As with response surface analysis, exploration can proceed iteratively. When an interesting new fit is found, the controller can be recentered and exploration continued around the new fit. The technique integrates easily with other dynamic graphical techniques, such as brushing and the use of sliders. The dynamic graphical technique is developed in this article primarily in the context of multiple linear regression. An example of the application of the technique to the Brownlee stack loss data set is presented and compared to the extensive analysis given by Daniel ...