نتایج جستجو برای: sample variance
تعداد نتایج: 498107 فیلتر نتایج به سال:
this thesis attempts to investigate the effects of prelistening activities on enhancing iranian efl learners` listening comprehension. the present study investigated ways in which learners` background knowledge could be activated in order to enhance their l2 listening comprehension by limiting the number of possible text interpretations prior to listening. the experiments conducted in this stud...
the main purpose of the present study was to investigate the relationship between listening proficiency and metacognitive listening strategies awareness among low, mid, and highly self-regulated students. three hundred and seventy one efl students participated in this study (all grade 3 and 4 high-school students who were studying in khansar in academic year 1391-92). to gather the data, three ...
BACKGROUND Confocal Laser Scanning Microscopy (CLSM) provides the opportunity to perform 3D DNA content measurements on intact cells in thick histological sections. So far, sample size has been limited by the time consuming nature of the technology. Since the power of DNA histograms to resolve different stemlines depends on both the sample size and the coefficient of variation (CV) of histogram...
System noise was analyzed in 77 Affymetrix 6.0 samples from a previous clinical study of copy number variation (CNV). Twenty-three samples were classified as eligible for CNV detection, 29 samples as ineligible and 25 were classified as being of intermediate quality. New software ("noise-free-cnv") was developed to visualize the data and reduce system noise. Fresh DNA preparations were more lik...
Variances in the American Community Survey are estimated using a replicate weight methodology (Fay, 1995). In counties with small sample sizes, the variance estimates of poverty statistics show wide variation as a function of sample size. Generalized Variance Functions (GVF) can be used to smooth out the uncertainty of the design-based variance estimate. We propose incorporating GVFs with small...
The paper introduces a family of approximate schemes that extend the process of computing sample mean in importance sampling from the conventional OR space to the AND/OR search space for graphical models. All the sample means are defined on the same set of samples and trade time with variance. At one end is the AND/OR sample tree mean which has the same time complexity as the conventional OR sa...
Mean-variance portfolios constructed using the sample mean and covariance matrix of asset returns perform poorly due to estimation error. Moreover, it is commonly accepted that estimation error in the sample mean is much larger than in the sample covariance matrix. For this reason, recent research has focused on the minimum-variance portfolio, which relies only on estimates of the covariance ma...
In analyzing the output process generated by a steady-state simulation, we often seek to estimate the expected value of the output. The sample mean based on a finite sample of size n is usually the estimator of choice for the steady-state mean; and a measure of the sample mean’s precision is the variance parameter, i.e., the limiting value of the sample size multiplied by the variance of the sa...
Nearest neighbor imputation (NNI) is a popular imputation method used to compensate for item nonresponse in sample surveys. Although previous results showed that the NNI sample mean and quantiles are consistent estimators of the population mean and quantiles, large sample inference procedures, such as asymptotic confidence intervals for the population mean and quantiles, are not available. For ...
the statistical analysis of spatial data is usually done under gaussian assumption for the underlying random field model. when this assumption is not satisfied, block bootstrap methods can be used to analyze spatial data. one of the crucial problems in this setting is specifying the block sizes. in this paper, we present asymptotic optimal block size for separate block bootstrap to estimate the...
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