The estimation of the costs of a product or project and the decisions based on these forecasts ar... more The estimation of the costs of a product or project and the decisions based on these forecasts are subject to much uncertainty relating to factors like unknown future developments. This has been addressed repeatedly in research studies focusing on different aspects of uncertainty; unfortunately, this interest has not yet been adopted in practice. One reason can be found in the inadequate representation of uncertainty. This paper introduces an experiment which engages different approaches to displaying cost forecasting information to gauge the consideration of uncertainty in the subsequent decision-making process. Three different approaches of displaying cost-forecasting information including the uncertainty involved in the data were tested, namely a three point trend forecast, a bar chart and a FAN-diagram. Furthermore, the effects of using different levels of contextual information about the decision problem were examined. The results show that decision makers tend to simplify the level of uncertainty from a possible range of future outcomes to the limited form of a point estimate. Furthermore, the contextual information made the participants more aware of uncertainty. In addition, the fan-diagram prompted 75.0% of the participants to consider uncertainty even if they had not used this type of diagram before; it was therefore identified as the most suitable method of graphical information display for encouraging decision makers to consider the uncertainty in cost forecasting.
International Journal of Production Economics, 2009
Empirical research suggests that quantitatively derived forecasts are very frequently judgemental... more Empirical research suggests that quantitatively derived forecasts are very frequently judgementally adjusted. Nevertheless, little work has been conducted to evaluate the performance of these judgemental adjustments in a practical demand/sales context. In addition, the relevant analysis does not distinguish between slow and fast moving items. Currently, there are neither conceptual developments nor empirical evidence on the issue of integrating judgements and statistical forecasts for slow/intermittent demand items. Moreover, no results have ever been reported on the stock control implications of these human judgements. Our work analyses monthly intermittent demand forecasts for the UK branch of a major international pharmaceutical company. The company relies upon a commercially available statistical forecasting system to produce forecasts that are subsequently judgementally adjusted based on marketing intelligence gathered by the company forecasters. The benefits of the intervention are evaluated by comparing the actual sales to system and final forecasts using both forecast accuracy and inventory control (accuracy implication) metrics. Our study allows insights to be gained on potential improvements to intermittent demand forecasting processes and, subsequently, the design effectiveness of Forecasting Support Systems.
ABSTRACT Bayes theorem is the normative method for revising probability forecasts using new infor... more ABSTRACT Bayes theorem is the normative method for revising probability forecasts using new information. However, for unaided forecasters its application can be difficult, effortful, opaque and even counter-intuitive. The study proposes two simple heuristics for approximating Bayes formula while yielding accurate decisions. Their performance was assessed where a decision is made on which of two events is most probable and where a choice is made between an option yielding an intermediate utility for something that is certain or for a gamble which will result in either a worse or better utility (“certainty or risk” decisions). For “most probable event” decisions the first heuristic always results in the correct decision when the reliability of the new information does not depend on which event will occur. In other cases, the second heuristic typically led to the correct decision for about 95% of “most probable event” decisions and 86% of “certainty or risk” decisions.
ABSTRACT I discuss evidence that supports several of the principles put forward in the paper by A... more ABSTRACT I discuss evidence that supports several of the principles put forward in the paper by Armstrong, Green, and Graefe (AGG), but argue that the packaging of these principles as a single “golden rule”’ and the use of the term “conservative” may lead to misunderstandings. Additional work should be carried out to investigate the extent to which these principles should be applied to probability and interval forecasts. Finally, good reasons may support why “rational” forecasters behave in ways that are inconsistent with the guidelines AGG provide in their golden-rule checklist.
... Also the inserted questions literature (eg Glover 1989) and the text comprehension literature... more ... Also the inserted questions literature (eg Glover 1989) and the text comprehension literature (eg McNamara, et al. ... text. Using the everyday task of programming a VCR, Duggan and Payne (2001) improved participants' retention of instructional information by prompting them to ...
... the latest information technology, with little attention to whether these new ... In this pap... more ... the latest information technology, with little attention to whether these new ... In this paper we investigate the psychology of a fairly standard forecasting task and then use this knowledge empirically to evaluate alternative computer-based de-cision support tools. ...
The estimation of the costs of a product or project and the decisions based on these forecasts ar... more The estimation of the costs of a product or project and the decisions based on these forecasts are subject to much uncertainty relating to factors like unknown future developments. This has been addressed repeatedly in research studies focusing on different aspects of uncertainty; unfortunately, this interest has not yet been adopted in practice. One reason can be found in the inadequate representation of uncertainty. This paper introduces an experiment which engages different approaches to displaying cost forecasting information to gauge the consideration of uncertainty in the subsequent decision-making process. Three different approaches of displaying cost-forecasting information including the uncertainty involved in the data were tested, namely a three point trend forecast, a bar chart and a FAN-diagram. Furthermore, the effects of using different levels of contextual information about the decision problem were examined. The results show that decision makers tend to simplify the level of uncertainty from a possible range of future outcomes to the limited form of a point estimate. Furthermore, the contextual information made the participants more aware of uncertainty. In addition, the fan-diagram prompted 75.0% of the participants to consider uncertainty even if they had not used this type of diagram before; it was therefore identified as the most suitable method of graphical information display for encouraging decision makers to consider the uncertainty in cost forecasting.
International Journal of Production Economics, 2009
Empirical research suggests that quantitatively derived forecasts are very frequently judgemental... more Empirical research suggests that quantitatively derived forecasts are very frequently judgementally adjusted. Nevertheless, little work has been conducted to evaluate the performance of these judgemental adjustments in a practical demand/sales context. In addition, the relevant analysis does not distinguish between slow and fast moving items. Currently, there are neither conceptual developments nor empirical evidence on the issue of integrating judgements and statistical forecasts for slow/intermittent demand items. Moreover, no results have ever been reported on the stock control implications of these human judgements. Our work analyses monthly intermittent demand forecasts for the UK branch of a major international pharmaceutical company. The company relies upon a commercially available statistical forecasting system to produce forecasts that are subsequently judgementally adjusted based on marketing intelligence gathered by the company forecasters. The benefits of the intervention are evaluated by comparing the actual sales to system and final forecasts using both forecast accuracy and inventory control (accuracy implication) metrics. Our study allows insights to be gained on potential improvements to intermittent demand forecasting processes and, subsequently, the design effectiveness of Forecasting Support Systems.
ABSTRACT Bayes theorem is the normative method for revising probability forecasts using new infor... more ABSTRACT Bayes theorem is the normative method for revising probability forecasts using new information. However, for unaided forecasters its application can be difficult, effortful, opaque and even counter-intuitive. The study proposes two simple heuristics for approximating Bayes formula while yielding accurate decisions. Their performance was assessed where a decision is made on which of two events is most probable and where a choice is made between an option yielding an intermediate utility for something that is certain or for a gamble which will result in either a worse or better utility (“certainty or risk” decisions). For “most probable event” decisions the first heuristic always results in the correct decision when the reliability of the new information does not depend on which event will occur. In other cases, the second heuristic typically led to the correct decision for about 95% of “most probable event” decisions and 86% of “certainty or risk” decisions.
ABSTRACT I discuss evidence that supports several of the principles put forward in the paper by A... more ABSTRACT I discuss evidence that supports several of the principles put forward in the paper by Armstrong, Green, and Graefe (AGG), but argue that the packaging of these principles as a single “golden rule”’ and the use of the term “conservative” may lead to misunderstandings. Additional work should be carried out to investigate the extent to which these principles should be applied to probability and interval forecasts. Finally, good reasons may support why “rational” forecasters behave in ways that are inconsistent with the guidelines AGG provide in their golden-rule checklist.
... Also the inserted questions literature (eg Glover 1989) and the text comprehension literature... more ... Also the inserted questions literature (eg Glover 1989) and the text comprehension literature (eg McNamara, et al. ... text. Using the everyday task of programming a VCR, Duggan and Payne (2001) improved participants' retention of instructional information by prompting them to ...
... the latest information technology, with little attention to whether these new ... In this pap... more ... the latest information technology, with little attention to whether these new ... In this paper we investigate the psychology of a fairly standard forecasting task and then use this knowledge empirically to evaluate alternative computer-based de-cision support tools. ...
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Papers by Paul Goodwin