Let $X_1, \dots, X_n$ denote a random sample from the PDF
$$f_{\varphi}(x)=
\begin{cases}
\varphi x^{\varphi - 1} &\text{if}\, 0 < x < 1, \varphi > 0\\
0 &\text{otherwise}
\end{cases}$$
This density function is a member of the one-parameter exponential family.
Let $A_i = - \log(X_i)$, wher...