Let the $p$-component vector $X$ be normally distributed with mean $\xi$ and covariance $\sigma^2I$ where $I$ denotes the identity matrix and $\sigma$ is known. For estimating $\xi$ with quadratic loss, it is known that $X$ is minimax but inadmissible for $p \geqq 3$. We obtain a family of estimators which dominate $X$ and are admissible. These estimators are, therefore, both minimax and admissible.
A Bayesian formulation of the problem of analysing data from a curvilinear regression of $y$ on $x_1, x_2, \cdots, x_r$ in order to predict a future value of $y$ is considered. The problem is to obtain a criterion to decide which is the best subset of $x_1, x_2, \cdots, x_r$ to perform this prediction. Under very strict assumptions the criterion obtained is shown to use the same statistic as the orthodox (least squares) approach.
Anbar (1971) and, independently, Abdelhamid (1971) have shown that if the density $g$ of the errors of estimates of function values is known, a transformation of observations leads to stochastic approximation methods which under mild conditions produce asymptotically efficient estimators (the first author considers the RM case, the second the RM and KW cases). This paper treats the RM case and shows that the same asymptotic result can be achieved without the knowledge of the…
In a previous paper, the authors introduced a new criterion of expectation consistency between probability distributions of discrete data given discrete parameter values and arbitrary posterior probability distributions for the parameter. It is here shown, under very weak assumptions, that expectation consistency implies that the posterior distributions are generalized Bayes. However when the posterior distributions are generalized Bayes, the implied prior distribution need…
In this paper it is shown that in order for the trimmed mean to be asymptotically normal, it is necessary and sufficient that the sample be trimmed at sample percentiles such that the corresponding population percentiles are uniquely defined. (The sufficiency of this condition is well known.) In addition, the (non-normal) limiting distribution of the trimmed mean when this condition is not satisfied is derived, and it is shown that in some situations the use of the trimmed…
D. L. Hanson · Gordon Pledger · F. T. Wright·刊期 1973-05-01 · 卷 1(3)·The Annals of Statistics已编入正刊
单调回归的一致性研究AI 解读
For each $t$ in some subset $T$ of $N$-dimensional Euclidean space let $F_t$ be a distribution function with mean $m(t)$. Suppose $m(t)$ is non-decreasing in each of the coordinates of $t$. Let $t_1, t_2,\cdots$ be a sequence of points in $T$ and let $Y_1, Y_2,\cdots$ be an independent sequence of random variables such that the distribution function of $Y_k$ is $F_{t_k}$. Estimators $\hat{m}_n(t; Y_1,\cdots, Y_n)$ of $m(t)$ which are monotone in each coordinate of $t$ and…
Suppose $g$ is a probability density on $R = (-\infty, +\infty)$ with a continuous derivative and with $I(g) = \int (g'/g)^2g < + \infty$. Suppose $\{\varepsilon_n\}$ is a sequence of positive numbers converging to zero and $V_i, Z_i$ are random variables, $Z_i \rightarrow 0$ with probability one and $V_n$ is conditionally (given $V_1, \cdots, V_{n-1}, Z_1, \cdots, Z_n$) distributed according to $g$. Estimates $h_n$ of $g'/g$ are constructed, which are based on $V_1 + Z_1, \cdots, V_n + Z_n$…
The present paper deals with the asymptotic theory of sequential confidence intervals of prescribed width $2d (d > 0)$ and prescribed coverage probability $1 - \alpha (0 < \alpha < 1)$ for the (unknown, per unit) strength of bundle of parallel filaments. In this context, certain useful convergence results on the empirical distribution and on the bundle strength of filaments are established and incorporated in the proofs of the main theorems. The results are the sequential…
Let $\Theta$ be an open subset of $R^k$ and for each $\theta \in \Theta$, let $X_1, \cdots, X_n$ be independent rv's defined on the probability space $(\mathscr{X}, \mathscr{A}, P_\theta)$, and let $p_{j, \theta}$ be the distribution of the rv $X_j$. Let $f_j(\bullet; \theta)$ be a specified version of the Radon-Nikodym derivative of $p_{j, \theta}$ with respect to a $\sigma$-finite measure $\mu$ and set $f_j(\theta) = f_j(X_j; \theta)$. Furthermore, for $\theta, \theta^\ast \in \Theta$…
We consider the partial order on the unit square; $s_1 = (x_1, y_1) \ll s_2 = (x_2, y_2)$ if and only if $x_i \leqq y_i$ for $i = 1, 2$, and say that a real-valued function $f$ is isotone if $s_1 \ll s_2$ implies that $f(s_1) \leqq f(s_2)$. Suppose that for each point, $s$, in the unit square we have a distribution with median $m(s)$ and $m(s)$ is isotone. In this paper we propose an isotone estimator for $m$ which we denote by $\hat{m}$ and give an algorithm for computing $\hat{m}$…
The minimum variance unbiased estimates are obtained when a sample is drawn from the power series distribution with unknown parameter $\lambda$ and unknown truncation parameter $\nu$. Unbiased tests of hypotheses are formulated.
Let $X_{(i\mid n)}$ be the $i$th smallest order statistic from a population with $\operatorname{pdf} f(x)$ and $\operatorname{cdf} F(x)$. When $\tilde{x}$ is the population median, $n$ is the sample size and $G(x) = F(x)(1 - F(x))$, the following are proved. \begin{equation*}\begin{split}E(X_{(n-i+1\mid n)}) + E(X_{(i\mid n)}) \\ = n(n - 2i + 1)\binom{n - 1}{i - 1} \sum^{\lbrack (n-2i+1)/2\rbrack}_{\nu = 0}\frac{(-1)^\nu}{n - 2i + 1 - \nu}\binom{n - 2i + 1 - \nu}{\nu} \\ \times \Psi_1(i - 1 + \nu),\end{split}\end{equation*}…
Let $Z_1, Z_2,\cdots$, be independent and identically distributed random variables and $\{c_{ijn}\}$ real numbers; put $T_n = \sum^n_{i,j = 1} c_{ijn}Z_iZ_j$. This paper gives conditions under which the distribution of $T_n - ET_n$ converges to the distribution of $\sum \Upsilon_m(Y_m^2 - 1)$ with $\{\Upsilon_m\}$ a real sequence and $Y_1, Y_2,\cdots$ independent $N(0, 1)$ random variables. The results are applied to the calculation of the asymptotic distributions of test…
A model for Bernoulli trials with Markov dependence is developed which possesses the usual frequency parameter $p = P\lbrack X_i = 1\rbrack$ and an additional dependence parameter $\lambda = P\lbrack X_i = 1 \mid X_{i-1} = 1\rbrack$. Sufficient statistics for the model with $p$ and $\lambda$ unknown are found and an exact closed form expression for their small sample joint distribution is given. Large sample distribution theory is also given and small sample variances…
Let $\{X(t), t = 0, \pm 1, \pm 2,\cdots\}$ be a $p$-dimensional, zero mean, stationary Gaussian time series with matrix-valued covariance function $R(u) = (r_{jk}(u)), u = 0, \pm 1, \pm 2, \cdots; j, k = 1, 2,\cdots, p$. Let $F(\omega)$ be the spectral density matrix of the time series (if $F(\omega)$ exists), and assume that $F(\omega)$ is positive definite for all $\omega\in(0, 2\pi\rbrack$. Let $\hat{F}_X(\omega_l)$ be an estimator of $F(\omega_l)$ formed by averaging $(2n + 1)$…
Consider a multiple regression problem in which the dependent variable and (3 or more) independent variables have a joint normal distribution. This problem was investigated some time ago by Charles Stein, who proposed reasonable loss functions for various problems involving estimation of the regression coefficients and who obtained various minimax and admissibility results. In this paper we continue this investigation and establish the inadmissibility of the traditional…
P. K. Sen · B. B. Bhattacharyya · M. W. Suh·刊期 1973-03-01 · 卷 1(2)·The Annals of Statistics已编入正刊
某些样本函数极值的极限行为AI 解读
For a sequence of random variables forming an $m$-dependent stochastic process (not necessarily stationary), asymptotic distribution and other convergence properties of the extremum of certain functions of the empirical distribution are studied. In this context, it is shown that the asymptotic probability of the classical Kolmogorov-Smirnov statistic exceeding any positive real number provides an upper bound for the corresponding probability when the underlying random…
The weak convergence of the sample df is studied under a given sequence of alternative hypotheses when parameters are estimated from the data. For a general class of estimators it is shown that the sample df, when normalised, converges weakly to a specified normal process. The results are specialised to the case of efficient estimation.
Robust test problems between two approximately known simple hypotheses can be formalized as minimax test problems between two composite hypotheses. We show that if the composite hypotheses can be described in terms of alternating capacities of order 2 (in the sense of Choquet), then the minimax tests are ordinary Neyman-Pearson tests between a fixed representative pair of simple hypotheses; moreover, the condition is in a certain sense also necessary. All the neighborhoods…
A study of relationships between confidence regions being Bayesian, and the existence of some generalizations of Fisher's notion of relevant subsets. For a betting scheme introduced by Buehler, and for finite parameter space, it is shown that non-Bayesian procedures allow a winning strategy for a statistician's adversary. It is further shown, for finite parameter space, non-Bayesian procedures must admit conditional confidence levels bounded away from the unconditional…
We show that, in a weak sense, as the cost of observation tends to zero, the shape of the continuation region of the Bayes solution for the exponential family problem given above is approximated by that of a corresponding problem for the Wiener process with drift. The approach is an extension of that used in Bickel and Yahav, Proc. Sixth Berkeley Symp. Math. Statist. Prob. (1971).
The Bayesian approach to statistical problems, though fruitful in many ways, has been rather unsuccessful in treating nonparametric problems. This is due primarily to the difficulty in finding workable prior distributions on the parameter space, which in nonparametric ploblems is taken to be a set of probability distributions on a given sample space. There are two desirable properties of a prior distribution for nonparametric problems. (I) The support of the prior…
Let $(X, \mathscr{A})$ be a measurable space and $\mathscr{P} \mid \mathscr{A}$ a family of probability measures. Given a sufficient sub-$\sigma$-field, we define the sufficiency operator by assigning to each integrable function a conditional expectation which is independent of $P \in \mathscr{P}$. The operator thus defined is $\mathscr{P}$-a.e. linear, monotone, idempotent, and expectation invariant for every $P \in \mathscr{P}$. Not all of these properties are necessary to…
Let the p-component vector X be normally distributed with mean ξ and covariance σ2I where I denotes the identity matrix and σ is known. For estimating ξ with quadratic loss, it is known that X is minimax but inadmissible for p≧3. We obtain a family of estimators which dominate X and are admissible. These estimators are, therefore, both minimax and admissible.
A Bayesian formulation of the problem of analysing data from a curvilinear regression of y on x1,x2,⋯,xr in order to predict a future value of y is considered. The problem is to obtain a criterion to decide which is the best subset of x1,x2,⋯,xr to perform this prediction. Under very strict assumptions the criterion obtained is shown to use the same statistic as the orthodox (least squares) approach.
Anbar (1971) and, independently, Abdelhamid (1971) have shown that if the density g of the errors of estimates of function values is known, a transformation of observations leads to stochastic approximation methods which under mild conditions produce asymptotically efficient estimators (the first author considers the RM case, the second the RM and KW cases). This paper treats the RM case and shows that the same asymptotic result can be achieved without the knowledge of the…
For each t in some subset T of N-dimensional Euclidean space let Ft be a distribution function with mean m(t). Suppose m(t) is non-decreasing in each of the coordinates of t. Let t1,t2,⋯ be a sequence of points in T and let Y1,Y2,⋯ be an independent sequence of random variables such that the distribution function of Yk is Ftk. Estimators m^n(t;Y1,⋯,Yn) of m(t) which are monotone in each coordinate of t and…
Suppose g is a probability density on R=(−∞,+∞) with a continuous derivative and with I(g)=∫(g′/g)2g<+∞. Suppose {εn} is a sequence of positive numbers converging to zero and Vi,Zi are random variables, Zi→0 with probability one and Vn is conditionally (given V1,⋯,Vn−1,Z1,⋯,Zn) distributed according to g. Estimates hn of g′/g are constructed, which are based on V1+Z1,⋯,Vn+Zn…
The present paper deals with the asymptotic theory of sequential confidence intervals of prescribed width 2d(d>0) and prescribed coverage probability 1−α(0<α<1) for the (unknown, per unit) strength of bundle of parallel filaments. In this context, certain useful convergence results on the empirical distribution and on the bundle strength of filaments are established and incorporated in the proofs of the main theorems. The results are the sequential…
Let Θ be an open subset of Rk and for each θ∈Θ, let X1,⋯,Xn be independent rv's defined on the probability space (X,A,Pθ), and let pj,θ be the distribution of the rv Xj. Let fj(∙;θ) be a specified version of the Radon-Nikodym derivative of pj,θ with respect to a σ-finite measure μ and set fj(θ)=fj(Xj;θ). Furthermore, for θ,θ∗∈Θ…
We consider the partial order on the unit square; s1=(x1,y1)≪s2=(x2,y2) if and only if xi≦yi for i=1,2, and say that a real-valued function f is isotone if s1≪s2 implies that f(s1)≦f(s2). Suppose that for each point, s, in the unit square we have a distribution with median m(s) and m(s) is isotone. In this paper we propose an isotone estimator for m which we denote by m^ and give an algorithm for computing m^…
The minimum variance unbiased estimates are obtained when a sample is drawn from the power series distribution with unknown parameter λ and unknown truncation parameter ν. Unbiased tests of hypotheses are formulated.
Let X(i∣n) be the ith smallest order statistic from a population with pdff(x) and cdfF(x). When x~ is the population median, n is the sample size and G(x)=F(x)(1−F(x)), the following are proved. E(X(n−i+1∣n))+E(X(i∣n))=n(n−2i+1)(i−1n−1)ν=0∑[(n−2i+1)/2]n−2i+1−ν(−1)ν(νn−2i+1−ν)×Ψ1(i−1+ν),…
Let Z1,Z2,⋯, be independent and identically distributed random variables and {cijn} real numbers; put Tn=∑i,j=1ncijnZiZj. This paper gives conditions under which the distribution of Tn−ETn converges to the distribution of ∑Υm(Ym2−1) with {Υm} a real sequence and Y1,Y2,⋯ independent N(0,1) random variables. The results are applied to the calculation of the asymptotic distributions of test…
A model for Bernoulli trials with Markov dependence is developed which possesses the usual frequency parameter p=P[Xi=1] and an additional dependence parameter λ=P[Xi=1∣Xi−1=1]. Sufficient statistics for the model with p and λ unknown are found and an exact closed form expression for their small sample joint distribution is given. Large sample distribution theory is also given and small sample variances…
Let {X(t),t=0,±1,±2,⋯} be a p-dimensional, zero mean, stationary Gaussian time series with matrix-valued covariance function R(u)=(rjk(u)),u=0,±1,±2,⋯;j,k=1,2,⋯,p. Let F(ω) be the spectral density matrix of the time series (if F(ω) exists), and assume that F(ω) is positive definite for all ω∈(0,2π]. Let F^X(ωl) be an estimator of F(ωl) formed by averaging (2n+1)…
For a sequence of random variables forming an m-dependent stochastic process (not necessarily stationary), asymptotic distribution and other convergence properties of the extremum of certain functions of the empirical distribution are studied. In this context, it is shown that the asymptotic probability of the classical Kolmogorov-Smirnov statistic exceeding any positive real number provides an upper bound for the corresponding probability when the underlying random…
On the Asymptotic Shape of Bayesian Sequential Tests of θ≦0 Versus θ>0 for Exponential Families
Let (X,A) be a measurable space and P∣A a family of probability measures. Given a sufficient sub-σ-field, we define the sufficiency operator by assigning to each integrable function a conditional expectation which is independent of P∈P. The operator thus defined is P-a.e. linear, monotone, idempotent, and expectation invariant for every P∈P. Not all of these properties are necessary to…