共查询到20条相似文献,搜索用时 15 毫秒
1.
In this paper we examine the consequences, for statistical analysis and interpretation, of the particulate nature of radioactive contamination of a nuclear weapons test site. We propose a probabilistic model which incorporates the particulate nature of the contamination and which is simple enough to be statistically fitted to the data. Parameter estimation involves the reconciliation and combination of measurements of (a) 59.5 ke V gamma rays from americium-241, a decay product of plutonium-241, using a portable medium resolution NaI detector, on a regular survey grid at a test site and (b) 59.5 ke V radiation from soil samples obtained at grid points. The implications of the model for measurement of levels of contamination are considered. 相似文献
2.
This paper considers an iterative method for obtaining maximum likelihood estimates for a contingency table derived from a clustered sampling model. Comparisons are made with other methods proposed in the literature. 相似文献
3.
David Haziza Guillaume Chauvet Jean-Claude Deville 《Australian & New Zealand Journal of Statistics》2010,52(3):303-319
Cut-off sampling consists of deliberately excluding a set of units from possible selection in a sample, for example if the contribution of the excluded units to the total is small or if the inclusion of these units in the sample involves high costs. If the characteristics of interest of the excluded units differ from those of the rest of the population, the use of naïve estimators may result in highly biased estimates. In this paper, we discuss the use of auxiliary information to reduce the bias by means of calibration and balanced sampling. We show that the use of the available auxiliary information related to both the variable of interest and the probability of being excluded enables us to reduce the potential bias. A short numerical study supports our findings. 相似文献
4.
MOMENT ESTIMATION IN THE CLASS OF BISEXUAL BRANCHING PROCESSES WITH POPULATION–SIZE DEPENDENT MATING
Miguel González Manuel Mota Alfonso Ramos 《Australian & New Zealand Journal of Statistics》2007,49(1):37-50
This paper concerns the estimation of the offspring mean vector, the covariance matrix and the growth rate in the class of bisexual branching processes with population‐size dependent mating. For the proposed estimators, some unconditional moments and some conditioned to non‐extinction are determined and asymptotic properties are established. Confidence intervals are obtained and, as illustration, a simulation example is given. 相似文献
5.
C. A. McGilchrist R. L. Sandland J. L. Hennessy 《Australian & New Zealand Journal of Statistics》1983,25(2):321-328
Recursive methods in regression have proved useful in providing diagnostic tools for checking the model as well as checking the stability of the model over time. Such methods are now extended to deal with the problems of singularity that arise when one variable is completely confounded with previously fitted variables up to a particular time point. The problem is solved by setting it in the framework of the general linear model with dependent errors. 相似文献
6.
《统计学通讯:理论与方法》2013,42(9):1499-1514
ABSTRACT In a regression model with a random individual and a random time effect explicit representations of the nonnegative quadratic minimum biased estimators of the corresponding variances are deduced. These estimators always exist and are unique. Moreover, under normality assumption of the dependent variable unbiased estimators of the mean squared errors of the variance estimates are derived. Finally, confidence intervals on the variance components are considered. 相似文献
7.
A. D. Joffe 《Australian & New Zealand Journal of Statistics》1966,8(1):28-31
A stochastic model is proposed for the distribution of the number of particles in a sample of air-borne mine dust, and it, is shown that in special circumstances the distribution will be that of a Poisson variate.
I am indebted to Professor Bartlett for drawing my attention to his own more general result and to the referee for the suggestion that led to the unconditional result of Section 4. 相似文献
I am indebted to Professor Bartlett for drawing my attention to his own more general result and to the referee for the suggestion that led to the unconditional result of Section 4. 相似文献
8.
《统计学通讯:理论与方法》2013,42(8):1251-1257
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《统计学通讯:理论与方法》2013,42(6):961-975
ABSTRACT The paper deals with an improvement of the well-known Kaplan–Meier estimator of survival function when the censoring mechanism is random and independent of the failure times. Small sample size properties of the new estimator, as well as the original Kaplan–Meier estimator are inspected by means of Monte Carlo simulations. It follows from the simulations that the proposed estimator prevails with respect to some basic statistical characteristics. 相似文献
11.
《随机性模型》2013,29(1):1-24
A sufficient condition is proved for geometric decay of the steady-state probabilities in a quasi-birth-and-death process having a countable number of phases in each level. If there is a positive number η and positive vectors x = (x i) and y = (y j ) satisfying some equations and inequalities, the steady-state probability π mi decays geometrically with rate η in the sense π mi ~ cη m x i as m → ∞. As an example, the result is applied to a two-queue system with shorter queue discipline. 相似文献
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A Markov Renewal Process (M.R.P.) is one which records at each time t , the number of times a system visits each of m states in time t , if the transitions from state to state are according to a Markov chain and if the time required for each successive move is a random variable whose distribution function (d.f.) depends on the two states between which the move is made. In this paper, the distribution of the number of times each state is visited in an arbitrary interval (t0 , t0 +t) is derived. Asymptotic expressions for the mean and variance of this distribution are also obtained. 相似文献
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R. M. Clark 《Australian & New Zealand Journal of Statistics》1983,25(2):227-237
The Fisher distribution is frequently used as a model for the probability distribution of directional data, which may be specified either in terms of unit vectors or angular co-ordinates (co-latitude and azimuth). If, in practical situations, only the co-latitudes can be observed, the available data must be regarded as a sample from the corresponding marginal distribution. This paper discusses the estimation by Maximum Likelihood (ML) and the Method of Moments of the two parameters of this marginal Fisher distribution. The moment estimators are generally simpler to compute than the ML estimators, and have high asymptotic efficiency. 相似文献
16.
Traditional methods for estimating parameters in the generalized Pareto distribution have theoretical and computational defects. The moment estimator and the probability‐weighted moment estimator have low asymptotic efficiencies. They may not exist or may give nonsensical estimates. The maximum likelihood estimator, which sometimes does not exist, is asymptotically efficient, but its computation is complex and has convergence problems. The likelihood moment estimator is proposed, which is computationally easy and has high asymptotic efficiency. 相似文献
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T. Pukkila 《Australian & New Zealand Journal of Statistics》1979,21(2):121-128
The paper has its origin in the finding that the frequency-domain estimation of ARh4A models can produce estimates which may be remarkably biased. Both of the frequency-domain estimation methods considered in the paper are based on the frequency-domain likelihood function, which depends on the periodogram ordinates of the time series. It is found that, as estimates of the spectrum ordinates, the corresponding periodogram ordinates may contain a rather remarkable bias, which again causes bias in the estimates of parameters produced by a frequency-domain estimation method of an ARMA model. The bias is reduced by tapering the observed time series. An example is given of estimation experiments for simulated time series from a pure autoregressive process of order two. 相似文献
19.
This paper presents various estimators for estimating the population mean of the study variable y using information on the auxiliary variable x in the presence of non‐response. Properties of the suggested estimators are studied and compared with those of existing estimators. It is shown that the estimators suggested in this paper are among the best of all the estimators considered. An empirical study is carried out to demonstrate the performance of the suggested estimators and of others, and it is found that the empirical results support the theoretical study. 相似文献