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In the first case, the SD referred to {"SD = (b − a) / 6"} is the SD of the triangular distribution not the the standard error of the mean (which is unknown in this example). In the second case, this summation only works if all tasks times are independent, identically distributed, and normally
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479:{\displaystyle \operatorname {SD} ({\text{project}})={\sqrt {{1 \over n}\left(\operatorname {SD} ({\text{task}}_{1})^{2}+\operatorname {SD} ({\text{task}}_{2})^{2}+\cdots +\operatorname {SD} ({\text{task}}_{n})^{2}\right)}}}
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Technically, what is being referred to here is not the 'confidence level in E', the following is also technically incorrect:
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313:{\displaystyle {\sqrt {\sum {\operatorname {SD} ({\text{task}})^{2}}}}=\sum {\operatorname {SD} ({\text{task}})}}
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238:{\displaystyle \operatorname {SD} ({\text{project}})={\sqrt {\sum {\operatorname {SD} ({\text{task}})^{2}}}}}
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on
Knowledge. If you would like to participate, please visit the project page, where you can join
160:"Calculates the SD value for the total project work as SD (Project Work) = √(Σ SD (Task) 2)"
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distributed - plainly not often the case, otherwise you wouldn't be using 3pt estimates.
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Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
