Modeling the rework cycle: capturing multiple defects per task

Abstract

The rework cycle is at the heart of modeling projects, one of the major research and application areas in system dynamics. The current formulations for the rework cycle assume each task is either defective or not. Yet in many projects multiple defects can occur in one task. In this study we introduce a new rework cycle formulation that accounts for multiple defects per task and fl exibly captures the testing process. We compare this formulation with two established formulations from the literature. Analysis shows some differences in simulated projects' fi nish time and delivered quality across different models and we discuss how these differences depend on project characteristics and task structure. The new formulation could be especially useful when data on tasks, defects, and testing have different measures, and when each new defect in a task signifi cantly increases the chances of the task being rejected.

Structure-based System Dynamics analysis of engineering design processes

“…Phase Concurrency (Ford & Sterman, 1998aKasperek et al, 2014;Le et al, 2012; S. Lee & Sung Lim, 2007;Lin, 2006;Lin et al, 2008;Nasirzadeh et al, 2013;Parvan et al, 2013;Powell et al, 1999;Reichelt & Lyneis, 1999;Ruutu et al, 2011) Human Factors (Haslett & Sankaran, 2009;Kasperek et al, 2014;Laverghetta & Brown, 1999;Lisse, 2013;Munoz Hernandez et al, 2013;Reichelt & Lyneis, 1999;Ruutu et al, 2011;Williford & Chang, 1999) Staffing (Black & Repenning, 2001;Haslett & Sankaran, 2009;Joglekar & Ford, 2005;Lisse, 2013;Munoz Hernandez et al, 2013;Reichelt & Lyneis, 1999;Repenning, 2000;Taylor & Ford, 2006;Williford & Chang, 1999) Outsourcing (Lisse, 2013) Testing (Lin et al, 2008;Rahmandad & Hu, 2010) Tipping Point (Rahmandad & Al., 2005;Taylor & Ford, 2006) Cost and Schedule Foresight (Cooper & Lee, 2009;Lyneis et al, 2001) Process Improvement (D'Avino et al, 2005;Repenning & Sterman, 2002) Various studies exist on the topic of Phase Concurrency (Krishnan et al, 1997;…”

“…In Figure 4-5, this model is located in the middle. It is characterized by its simple structure that contains the minimum number of independent stocks to model processes with rework (Rahmandad & Hu, 2010). Also Kasperek, Lindinger et al (2014), Lisse (2013), Nasirzadeh et al (2013) and Parvan et al (2013) build their models based on this three-stock rework cycle.…”

“…Tasks Approved (Ford & Sterman, 1998a) Tasks Completed but not Checked (Rahmandad & Hu, 2010) Work in Progress (Le, 2013) Tasks to be Reworked (Lin, 2006;Lin et al, 2008) Tasks in Testing (Repenning, 2000) Work in Quality Assurance (Joglekar & Ford, 2005) Quality Assurance Backlog (Taylor & Ford, 2006) Known Rework (Cooper & Lee, 2009;Cooper, 1980;Cooper et al, 2002;Reichelt & Lyneis, 1999) The modeler of a System Dynamics model is encouraged to rethink the structure of the observed engineering design process and which states need to be captured in the rework cycle. Each crucial state has to be modeled by one stock.…”

“…Testing (Lin et al, 2008) Testing, Change Approval (Rahmandad & Hu, 2010) Error Rectification (Lin, 2006) Phase Task Change (Laverghetta & Brown, 1999) Hiring (Haslett & Sankaran, 2009;Reichelt & Lyneis, 1999) Hiring & Training (Munoz Hernandez et al, 2013;Williford & Chang, 1999) Change Generation (Parvan et al, 2013) Change Generation & Discovery (S. Lee & Sung Lim, 2007) Hiring & Training, Completed Work, Expended Effort (Lisse, 2013) Error Generation, Hiring & Training (Ruutu et al, 2011) SFC3) Consideration of influence of process concurrency in multi-phase projects…”

“…Pressure (Cooper et al, 2002;Le, 2013;Reichelt & Lyneis, 1999) Resources (Black & Repenning, 2001;Cooper, 1980;Cooper et al, 2002;Joglekar & Ford, 2005;Kasperek et al, 2014;Le, 2013;Lin, 2006;Rahmandad & Hu, 2010;Taylor & Ford, 2006) Overtime (Cooper et al, 2002;Le, 2013;Reichelt & Lyneis, 1999) Organizational Changes (Reichelt & Lyneis, 1999) Time to Completion (Cooper et al, 2002;Lisse, 2013) Human…”