1. INTRODUCTION 1.1.1. Variable Selection for Incomplete Data sets In statistical practice, many real-life data sets are incomplete for reasons like non-responses or drop-outs. When a data set is incomplete, practitioners frequently resort to a " case-deletion " strategy within which the incomplete cases are excluded from analysis and the complete cases are formed into a reduced rectangular com...

In deriving a regression model analysts often have to use variable selection, despite of problems introduced by datadependent model building. Resampling approaches are proposed to handle some of the critical issues. In order to assess and compare several strategies, we will conduct a simulation study with 15 predictors and a complex correlation structure in the linear regression model. Using sa...

Model selection procedures often use a fixed penalty, such as Mallows’ Cp, to avoid choosing a model which fits a particular data set extremely well. These procedures are often devised to give an unbiased risk estimate when a particular chosen model is used to predict future responses. As a correction for not including the variability induced in model selection, generalized degrees of freedom i...

Robust selection of variables in a linear regression model is investigated. Many variable selection methods are available, but very few methods are designed to avoid sensitivity to vertical outliers aswell as to leverage points. The nonnegative garrotemethod is a powerful variable selection method, developed originally for linear regression but recently successfully extended to more complex reg...

In this paper, we introduce a new methodology for Bayesian variable selection in linear regression that is independent of the traditional indicator method. A diagonal matrix $\mathbf{G}$ introduced to prior coefficient vector $\boldsymbol{\beta}$, with each $g_j$'s, bounded between $0$ and $1$, on serves as stabilizer corresponding $\beta_j$. Mathematically, promising has $g_j$ value close $0$,...

empowering employees in specialized and general qualifications fields is required for urban management organization (tehran municipality). planning and establishment of comprehensive system of electronic learning is considered the main goal of human resource and educational managers. . this study tried to investigate the feasibility and execution of electronic learning courses for in-service st...