Frank C. Kaminsky

Statistical Control Charts Based on a Geometric Distribution

In some production processes and administrative processes, the occurrence of certain events is best described by a geometric distribution. Control charts are developed for the total number of events and for the average number of events in a fixed number..

Six Sigma and Introductory Statistics Education.

A conflict exists between the way statistics is practiced in contemporary business environments and the way statistics is taught in schools of management. While businesses are embracing programs, such as six sigma and TQM, that bring statistical methods to the forefront of management decision making, students do not graduate with the skills to apply these methods effectively. Based on the concept of process thinking, it is argued that evolutionary rather than revolutionary changes should be made in the way statistics is taught. The difference between the process thinking approach and the classic statistical approach is illustrated using several business‐related examples.

PROCESS CAPABILITY INDICES: NOW AND IN THE FUTURE

An overview is provided on the use of process capability indices to measure the ability of a process to manufacture conforming product. After this overview, three characteristics of process capability indices are discussed. It is shown that alternative ..

THE EFFECT OF INSPECTOR ERRORS ON THE TRUE FRACTION NON-CONFORMING: AN INDUSTRIAL EXPERIMENT

This article describes the effect of Type I and Type II inspector errors on the true fraction nonconforming. Estimates of these errors from previous studies for different types of products and production processes are summarized. A procedure is outlined..

Simulating nonstationary Poisson processes: a comparison of alternatives including the correct approach

This paper describes three inexact methods that are commonly used to generate arrivals for a nonstation ary Poisson process and compares them to an exact method. Different patterns are assumed for the arrival rate as a function of time. The exact method is shown to produce accurate results, whereas all three inexact methods produce results that are sig nificantly different in a statistical sense. All four methods require similar amounts of computer time.

Process Capability Analysis for Processes With Either a Circular or a Spherical Tolerance Zone

A procedure to perform capability analysis for processes which must adhere to geometric dimensioning and tolerancing methods is developed. It takes into account the tolerance zone and the process variability. Assuming that the deviation from target for ..

Optimal spacing of wind turbines in a wind energy power plant

Abstract A nonlinear optimization problem is formulated to determine the optimal spacing between wind turbines to maximize instantaneous power from a one-line array of machines to be placed in a line parallel to constant wind direction. A specific example is then taken to illustrate the difference between optimal spacing and equidistant spacing.

Automated rescreening in cervical cytology. Mathematical models for evaluating overall process sensitivity, specificity and cost.

OBJECTIVE To develop mathematical models to assist decision makers with the difficult task of evaluating the use of automated rescreening in the process of screening cervical smears. STUDY DESIGN Using assumptions about incidence, per smear screening costs, and the sensitivity and specificity of cytotechnologists, pathologists and the rescreening device, basic probability models were developed to describe the overall sensitivity, specificity and cost of the screening process. RESULTS The optimal screening policy is highly dependent on assumptions, and an automated system can significantly affect the overall system cost and accuracy. CONCLUSION Mathematical planning models are valuable tools to assist decision makers in the design of a screening process for cervical smears.

Bivariate probability models for the description of average wind speed at two heights

Abstract Two bivariate density functions, the Rayleigh-shifted Rayleigh and the Rayleigh-normal are developed for use in modeling wind speed at two different heights. Using data from the Millstone nuclear power plant in Waterford, Connecticut, it is then shown that the Rayleigh-normal is a more appropriate model. The problem of estimating annual energy from a wind energy conversion system at one height using wind speed data from a lower height is then discussed. It is shown that the use of the Rayleigh distribution with a one-seventh wind shear coefficient underestimates energy production when compared to the use of the Rayleigh-normal. It is also shown that the use of higher wind shear coefficients results in overestimates of energy. These results were derived for a typical range of wind shear coefficients employed in conjunction with a one-parameter Rayleigh distribution.

Statistical and economic models for analysis and optimal design of laboratory screening policies for cervical cancer

This paper develops several statistical and economic models in order to analyze the accuracy and total cost of laboratory procedures commonly used in examining Pap smears for early indications of cervical cancer. In particular, the expected values, variances, and probability distributions are derived for the overall system sensitivity, overall system specificity, workload, and total system cost of several possible laboratory screening policies. These models are useful for analytically comparing possible alternative screening processes and for identifying the optimal minimum societal cost policy. Additionally, these models are used to show that the overall screening process never can have higher sensitivity nor lower specificity than the pathologist, that a rescreening rate of either 0% or 100% always will be economically optimal, and that total costs are highly variable period to period. While a primary objective of the present paper is to develop analytic and research tools, preliminary applied results suggest that significant improvements in sensitivity and reductions in total societal costs are possible by changing the policy currently required by the congressional Clinical Laboratory Improvement Amendments Act of 1988, typically with one to three repeated cytotechnologist screenings of presumed negative smears. Sensitivity analysis indicates these results are very dependent on cost and other inputs, and several directions for continued research therefore are described. Use of these models at the more micro laboratory and insurer levels, incorporation of automated rescreening devices, and extensions to mammography and other laboratory tests also are briefly discussed.