1,721,057 research outputs found
On the exact bootstrap distribution of linear statistics
No full textA method for evaluating the exact bootstrap distribution of a broad class of linear statistics is considered. First, the probability generating functions of the considered statistics are obtained in a closed form. Accordingly, the exact bootstrap distributions are computed by extracting the coefficients and the exponents of the corresponding probability generating functions. The proposed method is competitive with respect to existing ones both for simplicity and efficiency. In order to assess the performance of the method, some examples with real data sets are provided, while computer performance is assessed by means of a simulation
Some comments on design-based line-intersect sampling with segmented transects
No full textLine-intersect sampling based on segmented transects is adopted in many forest inventories to quantify important ecological indicators such as coarse woody debris attributes. By assuming a design-based approach, Affleck, Gregoire and Valentine (2005, Environ Ecol Stat 12:139-154) have recently proposed a sampling protocol for this line-intersect setting and have suggested an estimation method based on linear homogeneous estimators. However, their proposal does not encompass the estimation procedure currently adopted in some national forest inventories. Hence, the present paper aims to introduce a unifying perspective for both methods. Moreover, it is shown that the two procedures give rise to coincident estimators for almost all the usual field applications. Finally, some strategies for efficient segmented-transect replications are considered
A design-based approach to the estimation of plant density using point-to-plant sampling
No full textA relationship between plant density and the probability density function of the squared point-to-plant distance is found when a design-based approach is considered. The estimation of the probability density function (and consequently of plant density) is performed using a boundary kernel estimator. Accordingly, by means of a simulation study, the performance of the proposed estimator is evaluated with respect to some existing density estimators assuming some patterns of plant populations. Finally, an example from field data is considered
Probabilistic proof for the generalization of some well-known binomial identities
Full text linkWe provide probabilistic proofs for the generalized version of some celebrated identities involving binomial coefficients. The results are based on the properties of the Beta distribution
Local parametric density estimation methods in line transect sampling
No full textA semiparametric estimator of animal abundance based on local parametric density estimation is considered in line transect sampling. A key parametric model is initially assumed for the observed perpendicular distances and its parameters are estimated on the basis of standard likelihood methods. Subsequently, the estimation is nonparametrically corrected by using a local kernel-smoothed criterion function. In this case, the kernel bandwidth controls the amount of smoothing to be applied to the estimator, in the sense that large bandwidths are to be used if the key model is properly selected, while with small bandwidths the choice of the key parametric model is non-influential. The method provides consistent estimation, whatever key parametric model is chosen, and it improves over the purely nonparametric kernel estimation, since it takes into account that the probability density function of the observed distances is monotone decreasing and the so-called "shoulder" condition is often true. The results of a Monte Carlo study suggest that the proposed method performs very well with respect to the existing nonparametric and semiparametric estimators
A Monte Carlo integration approach to Horvitz-Thompson estimation in replicated environmental designs
No full textIn environmental protocols some replicates of the selected design are usually considered in order to estimate the target parameter. Subsequently, the Horvitz- Thompson (HT) estimator is computed for each design replicate and the overall estimator arises from the average of the single estimators. Since the target parameter may be expressed as a suitable integral of the HT estimator function, in the present paper the duality of Monte Carlo (MC) integration strategies and replicated-design procedures is shown
The unbalanced ranked-set sample sign test
No full textThis paper is concerned with the sign test under unbalanced ranked-set sampling (URSS), which constitutes a generalization of the usual ranked-set sampling (RSS). The null distribution properties of the URSS sign test are discussed. Accordingly, a URSS sign test optimized on the basis of the asymptotic relative efficiency criterion is introduced. The proposed test is compared with the RSS analog by means of both asymptotic relative efficiency properties as well as small-sample Monte Carlo power simulations. The results strongly encourage the use of the optimized URSS sign test
Editorial: Forum on recent developments on finitely additive probabilities and coherence
No full textA design-based randomized response procedure for the estimation of population proportion and sensitivity level
No full textA general design-based approach to randomized response surveys is proposed. The method is tailored for the joint estimation of the proportion of individuals in the population bearing a sensitive attribute and the proportion of individuals in the sensitive group declaring truthfully their status. The proposal is specialized to the case of simple random sampling without replacement, unequal probability sampling without replacement and stratified sampling. (C) 2007 Elsevier B.V. All rights reserved
The computation of the distribution of the sign test statistic for ranked-set sampling
No full textA simple and fast method for computing the exact distribution of the ranked-set sample sign test statistic is suggested. The proposed technique works even for very large sample sizes and is implemented by using the Mathematica package
- …
