Revisiting the PERT mean and variance

José Manuel HerrerI´as-Velasco, Rafael HerrerI´as-Pleguezuelo and Johan René van Dorp
Authors registered in the RePEc Author Service: Jose Manuel Herrerías-Velasco ()

European Journal of Operational Research, 2011, vol. 210, issue 2, 448-451

Abstract: Difficulties with the interpretation of the parameters of the beta distribution let Malcolm et al. (1959) to suggest in the Program Evaluation and Review Technique (PERT) their by now classical expressions for the mean and variance for activity completion for practical applications. In this note, we shall provide an alternative for the PERT variance expression addressing a concern raised by Hahn (2008) regarding the constant PERT variance assumption given the range for an activity's duration, while retaining the original PERT mean expression. Moreover, our approach ensures that an activity's elicited most likely value aligns with the beta distribution's mode. While this was the original intent of Malcolm et al. (1959), their method of selecting beta parameters via the PERT mean and variance is not consistent in this manner.

Keywords: Project; scheduling; PERT; Beta; distribution; Expert; judgment (search for similar items in EconPapers)
Date: 2011
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Citations: View citations in EconPapers (2)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:ejores:v:210:y:2011:i:2:p:448-451

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