Template:Weibull Probability Density Function

The One-Parameter Weibull Distribution
The one-parameter Weibull pdf is obtained by again setting $$\gamma=0 \,\!$$ and assuming $$\beta=C=Constant \,\!$$ assumed value or:


 * $$ f(T)={ \frac{C}{\eta }}\left( {\frac{T}{\eta }}\right) ^{C-1}e^{-\left( {\frac{T}{ \eta }}\right) ^{C}} \,\!$$

where the only unknown parameter is the scale parameter, $$\eta\,\!$$.

Note that in the formulation of the one-parameter Weibull, we assume that the shape parameter $$\beta \,\!$$ is known a priori from past experience on identical or similar products. The advantage of doing this is that data sets with few or no failures can be analyzed.