Template:Ald mean

The Mean or MTTF

 * •	The mean of the lognormal distribution, $$\bar{T}$$, is given by:


 * $$\bar{T}={{e}^{\bar{{T}'}+\tfrac{1}{2}\sigma _^{2}}}$$


 * •	The mean of the natural logarithms of the times-to-failure, $${{\bar{T}}^{^{\prime }}}$$, in terms of  $$\bar{T}$$  and  $${{\sigma }_{T}}$$  is given by:


 * $${{\bar{T}}^{\prime }}=\ln \left( {\bar{T}} \right)-\frac{1}{2}\ln \left( \frac{\sigma _{T}^{2}}+1 \right)$$