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Determine the natural parameter space of the exponential family of distribution of dimension one with $\chi=1, T=x,h=e^{-x^2}$. And $h(x)=e^{-|x|}$.

Work:

The natural parameter space is the set of $\theta$ such that the integral in $A(\theta)=log\int h(x)e^{\theta T(x) }dx$ is finite. Here,

$$\begin{split}\int_{-\infty}^{\infty}h(x)e^{\theta T(x)}&=\int e^{-x^2}e^{\theta x}dx\\ &=\int e^{-x^2+\theta x}dx\end{split}$$

which I do not know how to integrate. Is this...right?

Vons
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  • $-x^2 + \theta x = -\left(x - \frac \theta 2\right)^2 + \frac {\theta^2}4$ – Paul Sinclair Feb 05 '21 at 03:24
  • But how is "$h = e^{-x^2}$" and "$h(x) = e^{-|x|}$" at the same time? Are you abusing notation by having $h$ mean two things? Are are you mixing up two problems? – Paul Sinclair Feb 05 '21 at 03:29
  • Ah, thanks. lol that’s another part, to do it with another h(x). Should’ve put “part b” – Vons Feb 05 '21 at 03:33

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