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Article
Publication date: 10 April 2007

P.S. Hui, L.T. Wong and K.W. Mui

The aim of this paper is to propose alternative sampling schemes for indoor air quality assessments in which a balance between the sampling time required and number of…

Abstract

Purpose

The aim of this paper is to propose alternative sampling schemes for indoor air quality assessments in which a balance between the sampling time required and number of sampling points chosen is allowed.

Design/methodology/approach

CO2 was used as a reference to evaluate the existing and the proposed sampling schemes for average indoor pollutant concentration regarding the sampling time and sampling point density required and the probable errors induced at certain confidence levels of the measurement.

Findings

The results showed that increasing the number of sampling points would significantly reduce the corresponding sampling time required: at the same confidence level, doubling the sampling point density from 250 m2 to 500 m2 per measurement point would reduce the sampling time required from eight hours to three hours.

Research limitations/implications

The model parameters were determined from surveys for some typical offices in Hong Kong and therefore may require adaptation for use elsewhere.

Practical implications

A useful source of information in determining the number of sampling points chosen and the duration of the measurement needed according to the “acceptable” measurement uncertainty allowed.

Originality/value

Providing flexibility in IAQ assessment, the results would be useful to policymakers for making decisions on resources and manpower management for their respective sampling strategies while taking the uncertainties into account.

Details

Facilities, vol. 25 no. 5/6
Type: Research Article
ISSN: 0263-2772

Keywords

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Article
Publication date: 18 April 2008

J. Rodrigues Dias and Paulo Infante

The purpose of this paper is to investigate a new sampling methodology previously proposed for systems with a known lifetime distribution: the Predetermined Sampling

Abstract

Purpose

The purpose of this paper is to investigate a new sampling methodology previously proposed for systems with a known lifetime distribution: the Predetermined Sampling Intervals (PSI) method.

Design/methodology/approach

The methodology is defined on basis of system hazard cumulative rate, and is compared with other approaches, particularly those whose parameters may change in real time, taking into account current sample information.

Findings

For different lifetime distributions, the results obtained for adjusted average time to signal (AATS) using a control chart for the sample mean are presented and analysed. They demonstrate the high degree of statistical performance of this sampling procedure, particularly when used in systems with an increasing failure rate distribution.

Practical implications

This PSI method is important from a quality and reliability management point of view.

Originality/value

This methodology involves a process by which sampling instants are obtained at the beginning of the process to be controlled. Also this new approach allows for statistical comparison with other sampling schemes, which is a novel feature.

Details

International Journal of Quality & Reliability Management, vol. 25 no. 4
Type: Research Article
ISSN: 0265-671X

Keywords

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Article
Publication date: 1 August 2008

Cindy Johnson

The purpose of this paper is to examine commonly relied upon product sampling strategies, direct‐to‐consumer sampling and event sampling, to determine which method can…

Abstract

Purpose

The purpose of this paper is to examine commonly relied upon product sampling strategies, direct‐to‐consumer sampling and event sampling, to determine which method can deliver the greatest return on investment in a variety of situations.

Design/methodology/approach

The paper explores information and data collected via case studies in actual programs presented to brands. The trial, sample, and purchase numbers were actual averages from sampling effectiveness studies for these types of programs.

Findings

The paper identifies and segments different types of products and the method by which the products are most effectively implemented into trial and sampling programs. ICOM reveals hard statistics on the return on investment of programs utilizing multiple methods of sampling including point‐of‐use, direct mail and event sampling.

Practical implications

Marketers should follow the STEPS outlined in this study to apply the best brand sampling strategy for a given product. Knowledge of targeted consumer base along with careful pre‐event analysis will deliver the best return on investment for a trial campaign.

Originality/value

The paper reveals reasons for a growing shift in corporate budgeted marketing dollars from event marketing to direct consumer product sampling. While event sampling is not always an ineffective or inferior marketing method,the reader can discover methods for a pre‐event return on investment analysis that will reveal the sampling strategy sure to deliver the most “bang” for the marketing “buck”.

Details

Journal of Consumer Marketing, vol. 25 no. 5
Type: Research Article
ISSN: 0736-3761

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Article
Publication date: 1 January 1988

Elart von Collani and Klaus Meder

The most frequently used attribute sampling plan in MIL‐STD 105 D. In cases, however, when the quality level of incoming lots is generally sufficiently good, MIL‐STD 105 D…

Abstract

The most frequently used attribute sampling plan in MIL‐STD 105 D. In cases, however, when the quality level of incoming lots is generally sufficiently good, MIL‐STD 105 D often leads to unnecessarily high sampling cost. This can be avoided by using α‐optimal sampling plans. The authors outline the α‐optimal sampling scheme along with a simple procedure to determine α‐optimal sampling plans at workshop level. These plans depend on three parameters which have to be estimated from recorded data. In this article the effects of estimation errors in these parameters are investigated.

Details

International Journal of Quality & Reliability Management, vol. 5 no. 1
Type: Research Article
ISSN: 0265-671X

Keywords

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Article
Publication date: 1 October 1997

Atul Agarwal and R.C. Baker

The commitment to statistical process control programmes is becoming commonplace in US industry. However, some companies are experiencing failure of these programmes…

Abstract

The commitment to statistical process control programmes is becoming commonplace in US industry. However, some companies are experiencing failure of these programmes, particularly in multi‐strata (population) production processes. Even if such a process is in a state of statistical control, there is a high likelihood that one or more strata could drift away from the target owing to an assignable cause. The success of a QC programme depends on the ability of a quality control practitioner to detect this shift with a greater statistical power (sensitivity) and take corrective actions. Addresses the problem faced by the multi‐strata production process of a local manufacturing company in detecting a single stratum shift from the target with a high level of sensitivity. Proposes the selection of an appropriate sampling method (stratified or random) to have a strong bearing on the relative sensitivity of detecting the above shift in a single stratum. Develops power curves for the above mentioned process under stratified and random sampling scenarios, when a shift occurs in a single stratum. Examines the relationship of sample size to the threshold level of the stratum shift and the preferred sampling method.

Details

International Journal of Quality & Reliability Management, vol. 14 no. 7
Type: Research Article
ISSN: 0265-671X

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Article
Publication date: 16 October 2009

Mark Schreiner

The purpose of this paper is to provide a rigorous, statistically correct, and low‐cost way to audit sample a lender's loan portfolio, be they a microlender or other type…

Abstract

Purpose

The purpose of this paper is to provide a rigorous, statistically correct, and low‐cost way to audit sample a lender's loan portfolio, be they a microlender or other type of lender. No other paper applies this method to loan portfolios, even though it is a high demand application.

Design/methodology/approach

Standard techniques of audit sampling and dollar unit sampling with stratification are applied to the particular case of a microlender's portfolio. Unlike the audit sampling that almost all auditors use, no arbitrary rules of thumb are applied.

Findings

The paper finds that statistical audit sampling for a lender's loan portfolio is simple, rigorous, and inexpensive.

Practical implications

In audit sampling, most auditors use arbitrary rules of thumb and have no idea whether they are sampling enough items to actually be sure, with some desired level of confidence, that they have found no defects. This simple, inexpensive, and statistically rigorous technique will allow auditors who actually want to do a good job to quantify the precision of their statements in a very common application.

Originality/value

This paper combines several disparate threads from the statistical literature on audit sampling in a way that auditors (who are usually not statisticians) can apply them for auditing the quality of a lender's portfolio – microfinance or otherwise – which is a very common need.

Details

Managerial Finance, vol. 35 no. 12
Type: Research Article
ISSN: 0307-4358

Keywords

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Article
Publication date: 1 September 1998

Phillip M. Edwards

The red bead experiment (RBE) is very well‐known in total quality management. It was designed by Dr W.E. Deming to show managers several lessons in management and sampling

Abstract

The red bead experiment (RBE) is very well‐known in total quality management. It was designed by Dr W.E. Deming to show managers several lessons in management and sampling. The RBE has evolved over several decades and now has an accepted standard format. The RBE also serves as an introduction to control charts which are an important tool in statistical quality control. Surprisingly very little is known about the statistical properties of the RBE. This is most likely due to the fact that the RBE involves mechanical sampling and so is much more complicated than probability sampling. New methods are given for statistical analysis when mechanical sampling is involved (e.g. mechanical sampling of non‐uniform output in a manufacturing environment). This approach has specific applications to control charts which are a major tool in quality control. In a rigorous analysis, it is shown that p, the sample proportion of red beads in the RBE, is an unbiased estimator of the RBE process defect rate. Expressions are also found for the variance of p, enabling the calculation of control chart limits. Some of the techniques used can be applied to other mechanical sampling situations which may at first viewing seem intractable.

Details

International Journal of Quality Science, vol. 3 no. 3
Type: Research Article
ISSN: 1359-8538

Keywords

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Book part
Publication date: 15 April 2020

Joshua C. C. Chan, Chenghan Hou and Thomas Tao Yang

Importance sampling is a popular Monte Carlo method used in a variety of areas in econometrics. When the variance of the importance sampling estimator is infinite, the…

Abstract

Importance sampling is a popular Monte Carlo method used in a variety of areas in econometrics. When the variance of the importance sampling estimator is infinite, the central limit theorem does not apply and estimates tend to be erratic even when the simulation size is large. The authors consider asymptotic trimming in such a setting. Specifically, the authors propose a bias-corrected tail-trimmed estimator such that it is consistent and has finite variance. The authors show that the proposed estimator is asymptotically normal, and has good finite-sample properties in a Monte Carlo study.

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Book part
Publication date: 25 November 2003

Donna J Brogan

Health care insurance companies often conduct sample surveys of health plan members. Survey purposes include: consumer satisfaction with the plan and members’ health…

Abstract

Health care insurance companies often conduct sample surveys of health plan members. Survey purposes include: consumer satisfaction with the plan and members’ health status, functional status, health literacy and/or health services utilization outside of the plan. Vendors or contractors typically conduct these surveys for insurers. Survey results may be used for plans’ accreditation, evaluation, quality improvement and/or marketing. This article describes typical sampling plans and data analysis strategies used in these surveys, showing how these methods may result in biased estimators of population parameters (e.g. percentage of plan members who are satisfied). Practical suggestions are given to improve these surveys: alternate sampling plans, increasing the response rate, component calculation for the survey response rate, weighted analyses, and adjustments for unit non-response. Since policy, regulation, accreditation, management and marketing decisions are based, in part, on results from these member surveys, these important and numerous surveys need to be of higher quality.

Details

Reorganizing Health Care Delivery Systems: Problems of Managed
Type: Book
ISBN: 978-1-84950-247-4

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Book part
Publication date: 14 September 2007

Peter R. Stopher

Abstract

Details

Handbook of Transport Modelling
Type: Book
ISBN: 978-0-08-045376-7

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