[Solved] STAT5113 Homework5

1. One or more of the following problems might be graded.
2. Does the Multinomial distribution, having pmf

belong to an exponential family? Is the number of parameters k or k 1?

2. Verify whether or not the following distributions belong to an exponential family. If they do, specifythe natural sufficient statistic and the natural parameter.
   1. The Beta(,) distribution.
   2. The Rayleigh distribution, having pdf

.

1. The Weibull distribution, having pdf

.

Consider separately the case when is considered known and the case when it is not. B. The following problems will be graded.

3. Consider a sample of size n from the Unif (0,) distribution. Assume a Pareto prior distribution for , having pdf

where and are positive constants (sometimes called hyper-parameters).

1. Show that the posterior distribution of has again a Pareto distribution, specifying the formulas for updating the parameters and based on the observations.
2. Verify that the posterior distribution of based on the full data set is the same as the posterior based on the distribution of the sufficient statistic T = max{X_i : i = 1,,n}.

iid

4. Let X₁,,X_n N(,1).
   1. Find a one-dimensional sufficient statistic T and find its distribution.
   2. Let I() be Fisher information for the original model, and let I_T() be Fisher information for the reduced model determined by T. Show that I() = I_T().