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Cost-Efficient Designs for Assessing Work-Related Biomechanical Exposures
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences.
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 [en]
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: urn:nbn:se:uu:diva-185526ISBN: 978-91-554-8556-6 (print)OAI: oai:DiVA.org:uu-185526DiVA: diva2:572031
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
List of papers
1. Cost-Efficient Design of Occupational Exposure Assessment Strategies- A Review
Open this publication in new window or tab >>Cost-Efficient Design of Occupational Exposure Assessment Strategies- A Review
2010 (English)In: Annals of Occupational Hygiene, ISSN 0003-4878, E-ISSN 1475-3162Article in journal (Refereed) Published
Abstract [en]

When designing a strategy for collecting occupational exposure data, both economic and statistical performance criteria should be considered. However, very few studies have addressed the trade-off between the cost of obtaining data and the precision/accuracy of the exposure estimate as a research issue. To highlight the need of providing cost-efficient designs for assessing exposure variables in occupational research, the present review explains and critically evaluates the concepts and analytical tools used in available cost efficiency studies. Nine studies were identified through a systematic search using two algorithms in the databases PubMed and ScienceDirect. Two main approaches could be identified in these studies: ‘comparisons’ of the cost efficiency associated with different measurement designs and ‘optimizations’ of resource allocation on the basis of functions describing cost and statistical efficiency. In either case, the reviewed studies use simplified analytical tools and insufficient economic analyses. More research is needed to understand whether these drawbacks jeopardize the guidance on cost-efficient exposure assessment provided by the studies, as well as to support theoretical results by empirical data from occupational life.

Place, publisher, year, edition, pages
Oxford University Press, 2010
Keyword
Cost; error; information; performance; optimization
National Category
Environmental Health and Occupational Health
Research subject
Occupational and Environmental Medicine
Identifiers
urn:nbn:se:uu:diva-185394 (URN)
Projects
Kostandeffektiv datainsamling om fysisk arbetsbelastning
Funder
FAS, Swedish Council for Working Life and Social Research
Available from: 2012-11-23 Created: 2012-11-23 Last updated: 2017-12-07
2. Cost efficiency comparison of four video-based techniques for assessing upper arm postures
Open this publication in new window or tab >>Cost efficiency comparison of four video-based techniques for assessing upper arm postures
2012 (English)In: Ergonomics, ISSN 0014-0139, E-ISSN 1366-5847Article in journal (Refereed) Published
Abstract [en]

Many video-based techniques for assessing postures at work have been developed. Choosing the most appropriate technique should be based on an evaluation of different alternatives in terms of their ability to produce posture information at low input costs, i.e. their cost efficiency. This study compared four video-based techniques for assessing upper arm postures, using cost and error data from an investigation on hairdressers. Labour costs associated with the posture assessments from the video recordings were the dominant factor in the cost efficiency comparison. Thus, a work sampling technique associated with relatively large errors appeared, in general, to be the most cost-efficient because it was labour-saving. Measurement bias and other costs than labour cost for posture assessment influenced the ranking and economic evaluation of techniques, as did the applied measurement strategy, i.e. the numbers of video recordings and repeated assessments of them.

Place, publisher, year, edition, pages
Taylor & Francis, 2012
Keyword
precision; bias; input costs; measurement strategy; model specification
National Category
Medical and Health Sciences
Research subject
Occupational and Environmental Medicine
Identifiers
urn:nbn:se:uu:diva-185408 (URN)
Projects
Kostnadseffektiv datainsamling om fysisk arbetsbelastning
Funder
FAS, Swedish Council for Working Life and Social Research
Available from: 2012-11-23 Created: 2012-11-23 Last updated: 2017-12-07
3. Optimizing the Fraction of Expensive Direct Measurements in an Exposure Assessment Study
Open this publication in new window or tab >>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.

Keyword
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:nbn:se:uu:diva-185418 (URN)
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
4. Deriving Cost-Efficient Strategies for Observational Assessments of Postural Loads    
Open this publication in new window or tab >>Deriving Cost-Efficient Strategies for Observational Assessments of Postural Loads    
2012 (English)Article in journal (Other academic) Submitted
Abstract [en]

Studies aimed at optimizing resource allocation between different sampling stages are characterized by both simplicity and incompleteness in optimization and economic analysis. The aim of this study was therefore to completely resolve the allocation problem for a four-stage measurement strategy devoted to observational assessment of work-related postural loads with the precision of the mean estimate considered as ‘output’. The derived demand functions for inputs to the four stages were used to derive functions for the minimized cost and the maximized precision of the measurement strategy. The application of the theoretical results to a working posture assessment study led to increased cost efficiency of the measurement strategy investigated in the study. Under the additional constraint that the optimal values must be integers, optimization of this measurement strategy would result in either a 12% reduction in cost or a 7% increase in precision. 

Keyword
measurement strategy; demand function; technical efficiency; productive efficiency; cost function
National Category
Medical and Health Sciences
Research subject
Occupational and Environmental Medicine
Identifiers
urn:nbn:se:uu:diva-185419 (URN)
Projects
Kostnadseffektiv datainsamling om fysisk arbetsbelastning
Funder
FAS, Swedish Council for Working Life and Social Research
Available from: 2012-11-23 Created: 2012-11-23 Last updated: 2013-01-14

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