On the Monotonicity of a Certain Expectation
Khan, Rasul A.
Ann. Statist., Tome 19 (1991) no. 1, p. 1677-1680 / Harvested from Project Euclid
Let $\{X_n, n \geq 1\}$ be a sequence of random variables and let $P_\theta$ be a probability measure under which $(X_1, \ldots, X_n)$ have joint pdf's $f_n(X_1, \ldots, X_n, \theta) = L_n(\theta), n \geq 1$. Suppose $u_n = u_n(X_1, \ldots, X_n), n \geq 1$, are statistics such that $(u_n - c)(L_n(\theta') - L_n(\theta)) \geq 0, \forall (X_1, \ldots, X_n), n \geq 1$, for some constant $c = c(\theta,\theta'), \theta \neq \theta'$. For any increasing function $\psi$ and stopping time $T$, it is shown that $E_\theta\phi(u_T) \leq E_{\theta'}\phi(u_T)$, provided that one of the expectations is finite and $P_\theta(T < \infty) = P_{\theta'}(T < \infty) = 1$. The given result holds for a certain monotone likelihood ratio family and an exponential family in particular. This generalizes a result of Chow and Studden and provides a sequential version of a result of Lehmann.
Publié le : 1991-09-14
Classification:  Monotone likelihood ratio,  exponential family,  stopping time,  increasing,  expectation,  62L10,  62A99
@article{1176348272,
     author = {Khan, Rasul A.},
     title = {On the Monotonicity of a Certain Expectation},
     journal = {Ann. Statist.},
     volume = {19},
     number = {1},
     year = {1991},
     pages = { 1677-1680},
     language = {en},
     url = {http://dml.mathdoc.fr/item/1176348272}
}
Khan, Rasul A. On the Monotonicity of a Certain Expectation. Ann. Statist., Tome 19 (1991) no. 1, pp.  1677-1680. http://gdmltest.u-ga.fr/item/1176348272/