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Optimizing the Fraction of Expensive Direct Measurements in an Exposure Assessment Study
2014 (English)In: International Journal of Statistics in Medical Research, ISSN 1929-6029, Vol. 3, no 1, 44-54 p.Article in journal (Refereed) Published
Abstract [en]

When designing studies to assess occupational exposures, one persistent decision problem is the selection between two technical methods, where one is expensive and statistically efficient and the other is cheap and statistically inefficient. While a few studies have attempted to determine the relatively more cost-efficient design between two technical methods, no successful study has optimized the fraction of the expensive efficient method in a combined technique intended for long-run exposure assessment studies. The purpose of this study was therefore to optimize the fraction of the expensive efficient measurements by resolving a precision-requiring cost minimization problem. For an indefinite total number of measurements, the total cost of a working posture assessment study was minimized by performing only expensive direct technical measurements. However, for a definite total number of measurements, the use of combined techniques in assessing the posture could be optimal, depending on the constraints placed on the precision and on the research budget.

Place, publisher, year, edition, pages
2014. Vol. 3, no 1, 44-54 p.
Keyword [en]
combined technique; cost function; productive efficiency; cost savings; marginal cost-benefit ratio; diseconomies of scale
National Category
Medical and Health Sciences
Research subject
Occupational and Environmental Medicine
Identifiers
URN: urn:nbn:se:uu:diva-185418OAI: oai:DiVA.org:uu-185418DiVA: diva2:571674
Projects
Kostnadseffektiv datainsamling om fysisk arbetsbelastning
Funder
Forte, Swedish Research Council for Health, Working Life and Welfare
Available from: 2012-11-23 Created: 2012-11-23 Last updated: 2015-09-30Bibliographically approved
In thesis
1. Cost-Efficient Designs for Assessing Work-Related Biomechanical Exposures
Open this publication in new window or tab >>Cost-Efficient Designs for Assessing Work-Related Biomechanical Exposures
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Work-related disorders due to biomechanical exposures have been subject to extensive research. Studies addressing these exposures have, however, paid limited attention to an efficient use of resources in exposure assessment. The present thesis investigates cost-efficient procedures for assessment of work-related biomechanical exposures, i.e. procedures aiming at a proper balance between statistical and economic performance.

Paper I is a systematic review of tools used in literature providing cost-efficient data collection designs. Two main approaches were identified in nine publications, i.e. comparing cost efficiency among alternative data collection designs, and optimizing resource allocation between different stages of data collection, e.g. subjects and samples within subjects. The studies presented, in general, simplified analyses, in particular with respect to economics.

Paper II compared the cost-efficiency of four video-based techniques for assessing upper arm postures. The comparison was based both on a comprehensive model of cost and error and additionally on two simplified models. Labour costs were a dominant factor in the cost efficiency comparison. Measurement bias and costs other than labour cost influenced the rank and economic evaluation of the assessment techniques.

Paper III compared the cost efficiency of different combinations of direct and indirect methods for exposure assessments. Although a combination of methods could significantly reduce the total cost of obtaining a desired level of precision, the total cost was, in the investigated scenario, lowest when only direct measurements were performed. However, when the total number of measurements was fixed, a combination was the most cost efficient choice.

In Paper IV, demand functions were derived for a four-stage measurement strategy with the focus of either minimizing the cost for a required precision, or maximizing the precision for a predetermined budget. The paper presents algorithms for identifying optimal values of measurement inputs at all four stages, adjusted to integers, as necessary for practical application.

In summary, the thesis shows that it is important to address all sources of costs and errors associated with alternative measurement designs in any particular study, and that an optimal determination of samples at different stages can be identified in several cases not previously addressed in the literature.         

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2012. 70 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 848
Keyword
measurement strategy; postural loads; statistical performance; optimization; economic evaluation; resource allocation; input costs; cost function; returns to scale; elasticity
National Category
Medical and Health Sciences
Research subject
Occupational and Environmental Medicine
Identifiers
urn:nbn:se:uu:diva-185526 (URN)978-91-554-8556-6 (ISBN)
Public defence
2013-01-30, Arbets- och miljömedicin, Ulleråkersvägen 40, Uppsala, 13:00 (Swedish)
Opponent
Supervisors
Available from: 2013-01-09 Created: 2012-11-26 Last updated: 2013-02-11Bibliographically approved

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