Template:Three-parameter weibull distribution

The three-parameter Weibull pdf is given by:


 * $$ f(t)={ \frac{\beta }{\eta }}\left( {\frac{t-\gamma }{\eta }}\right) ^{\beta -1}e^{-\left( {\frac{t-\gamma }{\eta }}\right) ^{\beta }} $$

where:


 * $$ f(t)\geq 0,\text{ }t\geq 0\text{ or }\gamma $$


 * $$\beta>0\ \,\!$$


 * $$ \eta > 0 \,\!$$


 * $$ -\infty < \gamma < +\infty $$

and:


 * $$ \eta= \,\!$$ scale parameter, or characteristic life
 * $$ \beta= \,\!$$ shape parameter (or slope)
 * $$ \gamma= \,\!$$ location parameter (or failure free life)