On Retaining Extreme Value Outcomes in an Aging Chain With a Co-Flow Structure

Informações

Código: GCT637
Divisão: GCT - Gestão de Ciência, Tecnologia e Inovação
Tema de Interesse: Tema 08 - Inovação e Gestão de Projetos

Autores

Paulo Soares Figueiredo, Elisabeth Loiola

Resumo

In many situations, System Dynamics modelers have to capture attributes of itemstracked in an aging chain. Typically, the outflow of items from the stocks in these chainsdepends on the attributes tracked in the co-flow. However, these well known, classic modelsfail to account for a specific phenomenon - the screening of items. This study presents a newapplication of co-flows in aging chains: A co-flow that enables the process of screening, i.e.the process of either terminating or approving items, depending on an attribute. We model atwo-stage aging chain with a co-flow structure that tracks the number of items and theirrelated attributes. Managers at each stage must decide on capacity utilization of workforceand thresholds for minimum attribute values.The model structure presented here could have many applications, such as newproduct development (NPD) pipelines and other situations in which items go through asequence of stages and are screened, depending on a specific attribute (Net Present Value incase of NPD pipelines).There are some key structures endogenous to the process of screening, namely 1)Capacity adjustment (how the throughput of items will be adjusted), 2) Type of screening(minimum or maximum values can be selected according to the distribution of the populationof attributes) and 3) Relation between co-flow attribute and throughput. This last structuredetermines if changes in the co-flow attribute from one stage to the next will be affected bycapacity utilization, i.e. by how intensively resources (people) are used, affecting thethroughput. For example, in product development pipelines it is generally assumed thatprojects gain value as they are developed and taken to the next stage, and that the level ofvalue gain depends on how intensively project teams are working (Wheelwright and Clark,1992, pg. 91, Girotra at al, 2005). Attributes tracked in a co-flow are also affected by thescreening process itself since some attribute is lost owing to the termination of items. Forinstance, by selecting only items with high attributes, the average attribute of the survivingpopulation of items is increased.We study the structure of the screening problem by formulating a System Dynamicsmodel that tracks the number of items and their attributes at each stage within a co-flowstructure. We model the screening process by applying an extreme value probabilitydistribution function (PDF) to the population of attributes of items at each stage. These itemsare eliminated or approved depending on the percentage of items below or above a predeterminedthreshold. A detailed explanation about the extreme value PDF is found in section3.Such model allows us to explore the question of how the screening process should bedeveloped to account for the successive selection of the items with higher attributes.Implications of the new system dynamics structures are discussed in the final section.

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