# Tagged Questions

0answers
24 views

### Modeling conditional variance (heteroskedasticity) using the gamma distribution

The application is that I want to know how $X$ maps not only to $y$, but to the variance of $y$. I think I've worked out a reasonable solution for doing so using the gamma distribution and the ...
0answers
212 views

### Heteroskedasticity - residual plot interpretation

I am plotting a residual plot to test for heteroskedasticity. The Breusch-Pagan test is significant and therefore I am suspecting there is evidence on heteroskedasticity. The question is: (a) How ...
1answer
154 views

### Heteroskedasticity and residuals normality

I have a linear regression that's quite good, I guess (it's for a university project so I don't really have to be super accurate). Point is, if I plot the residuals vs. predicted values, there is ...
1answer
163 views

### QQ plot is consistent with normality when subgroups are non-normal

I have read that for a one way ANOVA, you should check that the model residuals are normally distributed. If the variance of each group is homogeneous then this implies that the residuals with each ...
1answer
197 views

### ANOVA:How to detect non-normality with a QQPlot in the presence of non-homogeneous variance

This is a pretty general question but, I often find statistical textbooks claiming that, in order to justify the within groups normality assumption of a one way ANOVA, you can look at a QQ plots of ...
1answer
213 views

### Should raw data or residuals be used to check homogeneity of variance?

Unexpectedly for me (!) I've recently learnt that: "We have assumed that the error terms, $\epsilon_{ij}$, of the variates in each sample will be independent, that the variances of the error terms ...
0answers
313 views

### Simultaneous heteroscedasticity and heavy tails in a regression model

I'm trying to create a prediction model using regression. This is the diagnostic plot for the model that I get from using lm() in R: What I read from the Q-Q plot is that the residuals have a ...
2answers
429 views

### Model errors, residuals and heteroscedasticity

I have a quick question about the correct way to describe variance functions when seeking to cope with heteroscedasticity. As I understand it the statistical error of a model represents the departure ...
3answers
1k views

### Advice on explaining heterogeneity / heteroscedasticty

I am looking for any help, advice or tips in how to explain heterogeneity / heteroscedasticity to biologists in my department. In particular I want to explain why its important to look for it and deal ...