Simulation in manufacturing and business: A review

Copyright @ 2009 Elsevier B.V.This paper reports the results of a review of simulation applications published within peer-reviewed literature between 1997 and 2006 to provide an up-to-date picture of the role of simulation techniques within manufacturing and business. The review is characterised by three factors: wide coverage, broad scope of the simulation techniques, and a focus on real-world applications. A structured methodology was followed to narrow down the search from around 20,000 papers to 281. Results include interesting trends and patterns. For instance, although discrete event simulation is the most popular technique, it has lower stakeholder engagement than other techniques, such as system dynamics or gaming. This is highly correlated with modelling lead time and purpose. Considering application areas, modelling is mostly used in scheduling. Finally, this review shows an increasing interest in hybrid modelling as an approach to cope with complex enterprise-wide systems

Looking inside the black box : a theory-based process evaluation alongside a randomised controlled trial of printed educational materials (the Ontario printed educational message, OPEM) to improve referral and prescribing practices in primary care in Ontario, Canada

Background: Randomised controlled trials of implementation strategies tell us whether (or not) an intervention results in changes in professional behaviour but little about the causal mechanisms that produce any change. Theory-based process evaluations collect data on theoretical constructs alongside randomised trials to explore possible causal mechanisms and effect modifiers. This is similar to measuring intermediate endpoints in clinical trials to further understand the biological basis of any observed effects (for example, measuring lipid profiles alongside trials of lipid lowering drugs where the primary endpoint could be reduction in vascular related deaths). This study protocol describes a theory-based process evaluation alongside the Ontario Printed Educational Message (OPEM) trial. We hypothesize that the OPEM interventions are most likely to operate through changes in physicians' behavioural intentions due to improved attitudes or subjective norms with little or no change in perceived behavioural control. We will test this hypothesis using a well-validated social cognition model, the theory of planned behaviour (TPB) that incorporates these constructs. Methods/design: We will develop theory-based surveys using standard methods based upon the TPB for the second and third replications, and survey a subsample of Ontario family physicians from each arm of the trial two months before and six months after the dissemination of the index edition of informed, the evidence based newsletter used for the interventions. In the third replication, our study will converge with the "TRY-ME" protocol (a second study conducted alongside the OPEM trial), in which the content of educational messages was constructed using both standard methods and methods informed by psychological theory. We will modify Dillman's total design method to maximise response rates. Preliminary analyses will initially assess the internal reliability of the measures and use regression to explore the relationships between predictor and dependent variable (intention to advise diabetic patients to have annual retinopathy screening and to prescribe thiazide diuretics for first line treatment of uncomplicated hypertension). We will then compare groups using methods appropriate for comparing independent samples to determine whether there have been changes in the predicted constructs (attitudes, subjective norms, or intentions) across the study groups as hypothesised, and will assess the convergence between the process evaluation results and the main trial results.The OPEM trial and OPEM process evaluation are funded by the Canadian Institute of Health Research (CIHR). The OPEM process evaluation study was developed as part of the CIHR funded interdisciplinary capacity enhancement team KT-ICEBeRG. Gaston Godin, Jeremy Grimshaw and France Légaré hold Canada Research Chairs. Louise Lemyre holds an R.S. McLaughlin Research Chair

Exploring the economic implications of a group-based lifestyle intervention for middle-aged adults with chronic schizophrenia and co-morbid type 2 diabetes

Objective: People with schizophrenia are at elevated risk of having type 2 diabetes, compared to the general population. Although there is a growing body of literature on the effectiveness of behavioural interventions to improve physical activity levels and healthy eating habits, there are very few economic evaluations conducted for people with severe mental illness and physical health problems. The aim of this study is to explore the cost-effectiveness of group-based lifestyle interventions for middle-aged adults with enduring long-term schizophrenia and co-morbid type 2 diabetes. Methods: Deterministic decision analytical modelling techniques are applied to explore cost-effectiveness based on the findings from a systematic review on this population. The intervention refers to a group-based lifestyle intervention, which is a combination of exercise, diet and diabetes education over 6 months. The intervention costs are estimated to reflect the UK local context. Results: From the UK National Health Service perspective, the group-based lifestyle intervention is potentially cost-effective, relative to usual care. It costs £80 to achieve an additional unit of Body Mass Index (BMI) lost and the incremental cost-effectiveness ratio is just below £700 to gain an extra Quality Adjusted Life Year, which lies well within the conventionally acceptable threshold values in the UK. Conclusions: Group based life style intervention for this population is effective and can be cost-effective in reducing BMI and improving diabetes knowledge, at least in the short-term. More co-ordinated policies among relevant sectors are required to facilitate behavioural change and better maintain an improved lifestyle. An integrated approach is needed to make this more sustainable in the long-term