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581.
Dinesh S. Bhoj Mohammad Ahsanullah 《Biometrical journal. Biometrische Zeitschrift》1994,36(2):153-163
Consider the two linear regression models of Yij on Xij, namely Yij = βio + βij, Xij + Eij = 1, 2,…, ni, i = 1, 2, where Eij are assumed to be normally distributed with zero mean and common unknown variance σ2. The problem of estimating the conditional mean of Y1 for a given value of X1 is considered when it is a priori suspected that β10 = β20 and β11 = β21. The preliminary test estimator is proposed. The exact expressions for the bias and the mean square error of the estimator are derived. The relative efficiency of the new estimator to the usual least square estimator based on the first regression alone is computed and is used to determine the appropriate value of the significance level of the preliminary test β10 = β20 and β11 = β21. 相似文献
582.
The jackknife estimate of a Kaplan--Meier integral 总被引:1,自引:0,他引:1
We derive an explicit formula for the jackknife estimate ofa Kaplan-Meier integral. From this the asymptotic analysis ofthe jackknifed Kaplan-Meier process becomes straightforward.In a small simulation study it is demonstrated that jackknifingmay lead to a considerable reduction of the bias. 相似文献
583.
The problem of estimation of ratio of population proportions is considered and a difference-type estimator is proposed using auxiliary information. The bias and mean squared error of the proposed estimator is found and compared to the usual estimator and also to WYNN'S (1976) type estimator. An example is included for illustration. 相似文献
584.
A fast algorithm for the exact likelihood of stationary and partially nonstationary vector autoregressive-moving average processes 总被引:1,自引:0,他引:1
An expression for the likelihood function of a stationary vectorautoregressive-moving average process is developed. The expressionis very efficient numerically and applies to any stationarybut not necessarily invertible model. In particular, when themultivariate process is autoregressive, the exact likelihoodcan be evaluated with a small number of operations dependingon the order of the autoregressive operator and the processdimension, but not on the size of the observed series. The expressionalso provides an efficient method for the evaluation of theexact likelihood of a partially nonstationary vector autoregressive-movingaverage process, for which the determinant of the autoregressiveoperator has at least one unit root and the remaining rootsare outside the unit circle. This method does not require differencingthe series, so that complications caused by over-differencingthe series, such as noninvertibility and parameter identifiabilityproblems, are avoided. The results for autoregressive modelsare also applied to testing the stationarity and invertibilityof any autoregressive-moving average model with given parametervalues. 相似文献
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Zi Jin Sisi Chen Yingying Dai Chenhong Bao Shuling Ye Yuheng Zhou Yiyi Wang Shenghai Huang Yuanyuan Wang Meixiao Shen Dexi Zhu Fan Lu 《Journal of biophotonics》2020,13(8)
Current elastography techniques are limited in application to accurately assess spatially resolved corneal elasticity in vivo for human eyes. The air‐puff optical coherence elastography (OCE) with an eye motion artifacts correction algorithm is developed to distinguish the in vivo cornea vibration from the eye motion and visualize the Lamb wave propagation clearly in healthy subjects. Based on the Lamb wave model, the phase velocity dispersion curve in the high‐frequency is calculated to obtain spatially resolved corneal elasticity accurately with high repeatability. It is found that the corneal elasticity has regional variations and is correlated with intraocular pressure, which suggests that the method has the potential to provide noninvasive measurement of spatially resolved corneal elasticity in clinical practice. 相似文献
587.
A. R. Sen 《Biometrical journal. Biometrische Zeitschrift》1983,25(4):383-391
In this paper we will summarize some of the important sampling and non-sampling errors with special reference to the mail surveys on migratory game birds and aerial surveys on breeding birds in North America. Where possible, methods for controlling the errors will be indicated. 相似文献
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