This paper uses a least squares regression analysis to verify the well-known PERT estimate of the mean activity time as a weighted average of the optimistic (a), most likely or modal (m) and pessimistic (b) activity times in the classical formula: ûx = ( a + am + b )/6, and the estimate of the standard deviation of activity duration as one-sixth of the range: σx = (b-a)/6. Based on properties of the beta distribution, the paper shows also that there are theoretical grounds for using these estimates for a specified range of modal activity times, because in this range, ûx closely approximates the actual relationship between the mean and the mode.
Abdel-Fattah, I. (1992). Validation of Certain Statistics for Stochastic PERT Networks. The Egyptian Statistical Journal, 36(2), 291-306. doi: 10.21608/esju.1992.314867
MLA
Ibrahim Mousa Abdel-Fattah. "Validation of Certain Statistics for Stochastic PERT Networks", The Egyptian Statistical Journal, 36, 2, 1992, 291-306. doi: 10.21608/esju.1992.314867
HARVARD
Abdel-Fattah, I. (1992). 'Validation of Certain Statistics for Stochastic PERT Networks', The Egyptian Statistical Journal, 36(2), pp. 291-306. doi: 10.21608/esju.1992.314867
VANCOUVER
Abdel-Fattah, I. Validation of Certain Statistics for Stochastic PERT Networks. The Egyptian Statistical Journal, 1992; 36(2): 291-306. doi: 10.21608/esju.1992.314867
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