# model checking

1. ### mixed-effects models with (g)lmer in R and model selection

Mixed-effects models are wonderful for analyzing data, but it is always a hassle to find the best model, i.e. the model with the lowest AIC, especially when the number of predictor variables is large. Presently when trying to find the right model, I perform the following steps: 1) Start...
2. ### When to use validation and derivation cohort?

Hi everyone, I was wondering if there is any generic rules on when it's good to use a derivation and validation cohort on a dataset? So far I have only seen them being used for diagnostic tests. Also, if I use two datasets from two different studies to do this, do the datasets need to...
3. ### Explanatory variable a function of dependent variable

Hello, Does anyone know the proper terminology for the problem caused by regressing a dependent variable on a set of explanatory variables that includes a function of that very same dependent variable? For instance: y=B1*x+B2*f(y,g,h,...) + e Stumped for something that seems like a simple...
4. ### Model checking and generalized multilinear regression

Dear all, In my research I am analyzing the quality of game player softwares by making them play multiple times against a certain opponent and counting the number of victories. It seems to be very clear that the random variable of #victories should be modeled by a binomial distribution (as...
5. ### Repeated Measures ANOVA (Split-Plot ANOVA) analysis of residuals

Hi, how to process decent residual analysis in repeated measures? I know that the residuals should have normal distribution (altogether an in every level of repeated factor too), but is there any other way to examine the residuals? I am considering Levene's test to chcek if the variances...
6. ### What is model adequacy checking in anova?

In anova, we assume that the random error term \epsilon_{ij} is independent and identically distributed with mean 0 and variance \sigma^2 How can I check the normality assumption and independence assumption? Does model adequacy checking mean "Checking the normality assumption that...
7. ### Regression Model is signifianct but all explanatory variables are insignifiant!!!

Hi all, I need your help is the following: My Model is as the following Dependent variable is GDP per capita growth rate Explanatory variables are Domestic Investment (measured in Capital formation as percentage of GDP) Population Growth Human Capital (Measured in enrollment in...
8. ### Bayesian model checking: a problem with Gelman's chi-squared test

So, I foolishly tried to implement a test Gelman and his colleagues propose to determine whether observed data actually fits a model (Bayesian Data Analysis, Edition 1, p.172; or better: Gelman, Meng, Stern, 1996). If the test worked as advertised, it would be really useful--an omnibus way to...