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Statistical Perspective (statistical + perspective)

Distribution by Scientific Domains
Mathematics and Statistics60%

Selected Abstracts

Proper Assessment of the JFK Assassination Bullet Lead Evidence from Metallurgical and Statistical Perspectives

JOURNAL OF FORENSIC SCIENCES, Issue 4 2006
Erik Randich Ph.D.
ABSTRACT: The bullet evidence in the JFK assassination investigation was reexamined from metallurgical and statistical standpoints. The questioned specimens are comprised of soft lead, possibly from full-metal-jacketed Mannlicher-Carcano (MC), 6.5-mm ammunition. During lead refining, contaminant elements are removed to specified levels for a desired alloy or composition. Microsegregation of trace and minor elements during lead casting and processing can account for the experimental variabilities measured in various evidentiary and comparison samples by laboratory analysts. Thus, elevated concentrations of antimony and copper at crystallographic grain boundaries, the widely varying sizes of grains in MC bullet lead, and the 5,60 mg bullet samples analyzed for assassination intelligence effectively resulted in operational sampling error for the analyses. This deficiency was not considered in the original data interpretation and resulted in an invalid conclusion in favor of the single-bullet theory of the assassination. Alternate statistical calculations, based on the historic analytical data, incorporating weighted averaging and propagation of experimental uncertainties also considerably weaken support for the single-bullet theory. In effect, this assessment of the material composition of the lead specimens from the assassination concludes that the extant evidence is consistent with any number between two and five rounds fired in Dealey Plaza during the shooting. [source]

Environmental burden of disease: HRQoL and statistical perspectives

ENVIRONMETRICS, Issue 5 2004
Pranab Kumar Sen
Abstract Environmental toxicity and pollution mingled with substandard sanitation and public health practice can lead to serious health problems. Some of these toxics can be identified and subjected to preventive measures but together with some other major factors they form the environmental burden of disease, more seriously in developing countries. As a result, in health related quality of life risk assessments, especially relating to cancer of various types, as well as chronic and intestinal diseases, we need to incorporate toxicology as well as environmental epidemiology. Statistical perspectives in this challenging task are appraised with special attention to the arsenite contamination of the groundwater problem. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Comparison of updating techniques in transferability analysis of work trip mode choice models in developing countries

JOURNAL OF ADVANCED TRANSPORTATION, Issue 2 2010
Djoen San Santoso
Abstract This study analyzes the performances of updating techniques in transferability of mode choice models in developing countries. A model specification, estimated in Ho Chi Minh City, was transferred to Phnom Penh. Naïve transfer and four updating methods associated with small sized samples were used in the transfer process and were evaluated based on statistical perspective and predictive ability. The study also illustrates the problems faced in model transferability development, due to the lack of available and suitable data in Phnom Penh. This lack is strongly related to different methods and structures applied in collecting the data. Simplified approaches to the difficulties are proposed in the study. The results show that updating ASCs, updating both ASCs and scale parameter, and use of combined transfer estimators all produce significant improvement, both statistically and in predictability, in updating the model. The last two methods have proven to be superior to the first method, owing to the inclusion of transfer bias considerations in the estimations. However, small data samples should not have large transfer bias when using combined transfer estimators. It is also concluded that naïvely transferring a model is not recommended, and Bayesian updating should be avoided when transfer bias exists. Copyright © 2010 John Wiley & Sons, Ltd. [source]

A NOTE ON SAMPLING DESIGNS FOR RANDOM PROCESSES WITH NO QUADRATIC MEAN DERIVATIVE

AUSTRALIAN & NEW ZEALAND JOURNAL OF STATISTICS, Issue 3 2006
Bhramar Mukherjee
Summary Several authors have previously discussed the problem of obtaining asymptotically optimal design sequences for estimating the path of a stochastic process using intricate analytical techniques. In this note, an alternative treatment is provided for obtaining asymptotically optimal sampling designs for estimating the path of a second order stochastic process with known covariance function. A simple estimator is proposed which is asymptotically equivalent to the full-fledged best linear unbiased estimator and the entire asymptotics are carried out through studying this estimator. The current approach lends an intuitive statistical perspective to the entire estimation problem. [source]

Environmental burden of disease: HRQoL and statistical perspectives

ENVIRONMETRICS, Issue 5 2004
Pranab Kumar Sen
Abstract Environmental toxicity and pollution mingled with substandard sanitation and public health practice can lead to serious health problems. Some of these toxics can be identified and subjected to preventive measures but together with some other major factors they form the environmental burden of disease, more seriously in developing countries. As a result, in health related quality of life risk assessments, especially relating to cancer of various types, as well as chronic and intestinal diseases, we need to incorporate toxicology as well as environmental epidemiology. Statistical perspectives in this challenging task are appraised with special attention to the arsenite contamination of the groundwater problem. Copyright © 2004 John Wiley & Sons, Ltd. [source]