Homework 9
Optionally due in class, Tuesday November 26
From the text, problems 8.17(b,d), 8.18(b,d), 9.28, 9.34.
Note for 9.28: the question doesn't ask for it, but you should also
know how to find the value of c when the size of the test is specified.
Note for 9.34: just simplify the form of the test; you don't need to
find an explicit value or function for c.
Here are the problems written out, in case you don't have the text:
- 8.17: Let X_1, ..., X_n be a random sample from each of the
following distributions. In each case, find the MLE
theta-hat, var(theta-hat), 1/[ n*I(theta) ], where I(theta)
is the Fisher information of a single observation X, and
compare var(theta-hat) and 1/[ n*I(theta) ].
(b) N(theta, 1), -infinity < theta < infinity.
(d) Gamma(alpha=5, beta=theta), 0 < theta < infinity.
- 8.18: Referring to exercise 8.17 and using the fact that
theta-hat has an approximate N( theta, 1/[ n*I(theta) ] )
distribution, in each case construct an approximate 95
percent confidence interval for theta.
- 9.28: Let X_1, ..., X_n be a random sample from the normal
distribution N(theta, 1). Show that the likelihood ratio
principle for testing H_0: theta=theta' where theta' is
specified, against H_1: theta <> theta' (that's a "not
equal to") leads to the inequality |x-bar - theta'| >= c.
Is this a uniformly most powerful test of H_0 against H_1?
(Note: the question doesn't ask for it, but you should also
know how to find the value of c when the size of the test
is specified.)
- 9.34: A random sample X_1, ..., X_n arises from a distribution
given by:
H_0: f(x|theta) = 1/theta, 0 < x < theta, zero elsewhere,
or
H_1: f(x|theta) = (1/theta) * exp(-x/theta), 0 < x <
infinity, zero elsewhere.
Determine the likelihood ratio test associated with the
test of H_0 against H_1.
(Note: just simplify the form of the test; you don't need to
find an explicit value or function for c.)