Template:Ald sd: Difference between revisions

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====The Standard Deviation====
#REDIRECT [[Distributions_Used_in_Accelerated_Testing#The_Lognormal_Distribution]]
:* The standard deviation of the lognormal distribution, <math>{{\sigma }_{T}}</math>, is given by:
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::<math>{{\sigma }_{T}}=\sqrt{\left( {{e}^{2\bar{{T}'}+\sigma _{{{T}'}}^{2}}} \right)\left( {{e}^{\sigma _{{{T}'}}^{2}}}-1 \right)}</math>
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:* The standard deviation of the natural logarithms of the times-to-failure, <math>{{\sigma }_{{{T}'}}}</math>, in terms of  <math>\bar{T}</math>  and  <math>{{\sigma }_{T}}</math> is given by:
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::<math>{{\sigma }_{{{T}'}}}=\sqrt{\ln \left( \frac{\sigma _{T}^{2}}{{{{\bar{T}}}^{2}}}+1 \right)}</math>
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Latest revision as of 03:11, 16 August 2012