| 1. |
- Dehlendorff, Christian, et al.
(författare)
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Analysis of computer experiments with multiple noise sources
- 2010
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Ingår i: Quality and Reliability Engineering International. - : Wiley. - 0748-8017 .- 1099-1638. ; 26:2, s. 137-146
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we present a modeling framework for analyzing computermodels with two types of variations. The paper is based on a case study of an orthopedic surgical unit, which has both controllable and uncontrollable factors. Our results show that this structure of variation can be modeled effectively with linear mixed effects models and generalized additive models
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| 2. |
- Dehlendorff, Christian, et al.
(författare)
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Conditional Value at Risk as a Measure for Waiting Time in Simulations of Hospital Units
- 2010
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Ingår i: Quality Technology & Quantitative Management. - : Informa UK Limited. - 1684-3703 .- 1811-4857. ; 7:3, s. 321-336
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Tidskriftsartikel (refereegranskat)abstract
- The utility of conditional value at risk (CVaR) of a sample of waiting times as a measure for reducing long waiting times is evaluated with special focus on patient waiting times in a hospital. CVaR is the average of the longest waiting times, i.e., a measure at the tail of the waiting time distribution. The presented results are based on a discrete event simulation (DES) model of an orthopedic surgical unit at a university hospital in Denmark. Our analysis shows that CVaR offers a highly reliable performance measure. The measure targets the longest waiting times and these are generally accepted to be the most problematic from the points of view of both the patients and the management. Moreover, CVaR can be seen as a compromise between the well known measures: average waiting time and the maximum waiting time
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| 3. |
- Dehlendorff, Christian, et al.
(författare)
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Designing simulation experiments with controllable and uncontrollable factors
- 2008
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Ingår i: 2008 Winter Simuation Conference. - Piscataway, NJ : IEEE Communications Society. - 9781424427079 ; , s. 2909-2915
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Konferensbidrag (refereegranskat)abstract
- In this study we propose a new method for designing computer experiments inspired by the split plot designs used in physical experimentation. The basic layout is that each set of controllable factor settings corresponds to a whole plot for which a number of subplots, each corresponding to one combination of settings of the uncontrollable factors, is employed. The caveat is a desire that the subplots within each whole plot cover the design space uniformly. A further desire is that in the combined design, where all experimental runs are considered at once, the uniformity of the design space coverage should be guaranteed. Our proposed method allows for a large number of uncontrollable and controllable settings to be run in a limited number of runs while uniformly covering the design space for the uncontrollable factors
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| 4. |
- Dehlendorff, Christian, et al.
(författare)
-
Designing simulation experiments with controllable and uncontrollable factors for applications in healthcare
- 2011
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Ingår i: The Journal of the Royal Statistical Society, Series C. - : Oxford University Press (OUP). - 0035-9254 .- 1467-9876. ; 60:1, s. 31-49
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Tidskriftsartikel (refereegranskat)abstract
- We propose a new methodology for designing computer experiments that was inspired by the split-plot designs that are often used in physical experimentation. The methodology has been developed for a simulation model of a surgical unit in a Danish hospital. We classify the factors as controllable and uncontrollable on the basis of their characteristics in the physical system. The experiments are designed so that, for a given setting of the controllable factors, the various settings of the uncontrollable factors cover the design space uniformly. Moreover the methodology allows for overall uniform coverage in the combined design when all settings of the uncontrollable factors are considered at once
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