Tagged Questions

3
votes
1answer
105 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 ...
3
votes
1answer
129 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 ...
0
votes
0answers
56 views

finding the residual variance after correcting ordinal data for sex

I have a data set organized as: males, females as groups. Each individual has a "score" that is ordinal, ranking 0,1, or in another case, 0,1,2. I need to find the residual variation after correcting ...
2
votes
1answer
182 views

Checking normality of residuals in 2x2 mixed methods ANOVA

I am running a 2x2 mixed method ANOVA (with one between-group factor and one within-group factor - time 1 and time 2). I want to check whether the assumption of normality of residuals is met. When I ...
3
votes
0answers
162 views

Weighted regression for categorical variables

I have been trying to use weighted regression on some data where there are three categorical variables with the lm(y ~ A*B*C) command in R. This was to try ...
3
votes
2answers
501 views

Is SPSS giving the wrong residuals for a repeated measures design?

When running a repeated measures ANOVA in SPSS, it's possible to 'Save' the residuals as new variables in the data editor. But the values output do not match the residuals given in R, and seem to be ...
15
votes
3answers
8k views

ANOVA assumption normality/normal distribution of residuals

The Wikipedia page on ANOVA lists three assumptions, namely: Independence of cases – this is an assumption of the model that simplifies the statistical analysis. Normality – the distributions of the ...