A variable sampling plan based on the coefficient of variation for lots resubmission.

This study focuses on the issue of lots resubmission in inspection processes, which often arises when the initial inspection of a lot is suspected, marked as held, or not accepted. To address this problem, a novel variables sampling plan based on the coefficient of variation is proposed. The objective is to determine the sampling plan parameters that minimize the average sample number while satisfying the two-points of operating characteristic curve. Practical considerations are taken into account by providing tabulated values for the inspection sample size and acceptance criteria of the proposed plan. These tables incorporate various combinations of quality levels, considering commonly used producer's risk and consumer's risk. Furthermore, a comparative analysis between the proposed plan and a single sampling plan is conducted to highlight the advantages of the new approach. To illustrate the practical implementation of the proposed plan, an example is presented.

Assessing the suitability of sets-based approaches: estimating the discriminative power of risk models for ordinal outcome treatments.

BACKGROUND: In order to evaluate the discrimination performance of an ordinal model for improved disease screening, a new test was proposed where information was obtained across all samples simultaneously. METHODS: The ordinal c-index builds upon the volume under the surface methodology without focusing on the accompanying receiver operating characteristic surfaces. However, it can be simplified to an average of pairwise c-indexes. In this paper, a set-based estimate (information was obtained across all samples simultaneously) was proposed by summing all correctly ordered groups. The asymptotic distribution of this proposed estimate was derived using U-statistics. RESULTS: A predictive model was applied using the blood urea nitrogen/creatinine ratio to discriminate stroke in evolution in acute ischemic stroke patients, which could potentially be life-saving in emergency departments. CONCLUSIONS: By conducting Monte Carlo simulations, it was concluded that the measure proposed herein is a better choice for clinical use because of the asymmetry of the predicted probabilities of groups.

The optimal scaling combination of age and body mass index as an index of metabolic syndrome for postmenopausal Taiwanese women.

The aim of this study was to combine as a new index age with an anthropometric indicator of obesity that is more closely associated with metabolic syndrome (MS) risk than other anthropometric indicators for postmenopausal Taiwanese women. In this cross-sectional study, data were collected from 1128 postmenopausal women volunteers during the period from September 2008 to December 2009. Receiver operating characteristic (ROC) curves for assessing the risk of MS for postmenopausal Taiwanese women were computed for the optimal scaling combination (OSC) and anthropometric indicator of obesity. The area under the ROC curves of the OSC was significantly larger than those of the anthropometric indicator. OSC ≥ 4.98 was found to be the most prevalent cutoff point. The present investigation suggests that the OSC could be used in clinical practice as a simple parameter for the identification of postmenopausal Taiwanese women at risk of MS.

Using principal component analysis to develop a single-parameter screening tool for metabolic syndrome.

BACKGROUND: Metabolic syndrome (MS) is an important current public health problem faced worldwide. To prevent an "epidemic" of this syndrome, it is important to develop an easy single-parameter screening technique (such as waist circumference (WC) determination recommended by the International Diabetes Federation). Previous studies proved that age is a chief factor corresponding to central obesity. We intended to present a new index based on the linear combination of body mass index, and age, which could enhance the area under the receiver operating characteristic curves (AUCs) for assessing the risk of MS. METHODS: The labour law of the Association of Labor Standard Law, Taiwan, states that employers and employees are respectively obligated to offer and receive routine health examination periodically. Secondary data analysis and subject's biomarkers among five high-tech factories were used in this study between 2007 and 2008 in northern Taiwan. The subjects included 4712 males and 4196 females. The first principal component score (FPCS) and equal-weighted average (EWA) were determined by statistical analysis. RESULTS: Most of the metabolic and clinical characteristics were significantly higher in males than in females, except high-density lipoprotein cholesterol level. The older group (>45 years) had significantly lower values for height and high-density lipoprotein cholesterol level than the younger group. The AUCs of FPCS and EWA were significantly larger than those of WC and waist-to-height ratio. The low specificities of EWA and FPCS were compensated for by their substantially high sensitivities. FPCS ≥ 0.914 (15.4%) and EWA ≥ 8.8 (6.3%) were found to be the most prevalent cut off points in males and females, respectively. CONCLUSIONS: The Bureau of Health Promotion, Department of Health, Taiwan, had recommended the use of WC ≥ 90 cm for males and ≥ 80 cm for females as singular criteria for the determination of central obesity instead of multiple parameters. The present investigation suggests that FPCS or EWA is a good predictor of MS among the Taiwanese. However, the use of FPCS is not computationally feasible in practice. Therefore, we suggest that EWA be used in clinical practice as a simple parameter for the identification of those at risk of MS.