scholarly journals Skew-normal median regression model with applications

2020 ◽  
Vol 1616 ◽  
pp. 012079
Author(s):  
Xingyun Cao ◽  
Gege Wang ◽  
Liucang Wu
Keyword(s):  
Regression Model ◽  
Median Regression ◽  
Skew Normal

scholarly journals Bimodal Regression Model

2017 ◽  
Vol 40 (1) ◽  
pp. 65-83 ◽  
Author(s):  
Guillermo Domingo Martinez ◽  
Heleno Bolfarine ◽  
Hugo Salinas
Keyword(s):  
Regression Analysis ◽  
Regression Model ◽  
Regression Models ◽  
Error Term ◽  
Bimodal Distribution ◽  
New Model ◽  
Special Cases ◽  
Error Distributions ◽  
New Distribution ◽  
Skew Normal

Regression analysis is a technique widely used in different areas ofhuman knowledge, with distinct distributions for the error term. Itis the case, however, that regression models with bimodal responsesor, equivalently, with the error term following a bimodal distribution are notcommon in the literature, perhaps due to the lack of simple to dealwith bimodal error distributions. In this paper we propose a simpleto deal with bimodal regression model with a symmetric-asymmetricdistribution for the error term for which for some values of theshape parameter it can be bimodal. This new distribution containsthe normal and skew-normal as special cases. A realdata application reveals that the new model can be extremely usefulin such situations.

A nonparametric method for assessment of interactions in a median regression model for analyzing right censored data

2018 ◽  
Vol 28 (4) ◽  
pp. 1170-1187
Author(s):  
MinJae Lee ◽  
Mohammad H Rahbar ◽  
Hooshang Talebi
Keyword(s):  
Quantile Regression ◽  
Regression Model ◽  
Survival Data ◽  
Real Life ◽  
Simulation Studies ◽  
Median Regression ◽  
Right Censored Data ◽  
Censored Quantile Regression ◽  
Quantile Regression Model ◽  
The Impact

We propose a nonparametric test for interactions when we are concerned with investigation of the simultaneous effects of two or more factors in a median regression model with right censored survival data. Our approach is developed to detect interaction in special situations, when the covariates have a finite number of levels with a limited number of observations in each level, and it allows varying levels of variance and censorship at different levels of the covariates. Through simulation studies, we compare the power of detecting an interaction between the study group variable and a covariate using our proposed procedure with that of the Cox Proportional Hazard (PH) model and censored quantile regression model. We also assess the impact of censoring rate and type on the standard error of the estimators of parameters. Finally, we illustrate application of our proposed method to real life data from Prospective Observational Multicenter Major Trauma Transfusion (PROMMTT) study to test an interaction effect between type of injury and study sites using median time for a trauma patient to receive three units of red blood cells. The results from simulation studies indicate that our procedure performs better than both Cox PH model and censored quantile regression model based on statistical power for detecting the interaction, especially when the number of observations is small. It is also relatively less sensitive to censoring rates or even the presence of conditionally independent censoring that is conditional on the levels of covariates.

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