I know this is a german forum and I am sorry to post in english because I don't speak german
I want study the anxiety and depression scores in three types of pets with equal size ( 10 dogs, 10 cats and 10 hamsters). So we have here :
Independent variable : type of pet
Dependent variables : Anxiety scores - Depression scores.
I checked the following assumptions :
- The correlation between the dependant variables because r = 0,30
- We have homogeneity of between-group for depression scores (siginficance>0,05), but not for anxiety scores in (siginficance<0,05) so I employ Brown-Forsythe and Welch's F test concerning anxiety.
- We have homogeneity of variance-covariance matrices because Sig.>0,01, so the correlation between the dependant variables is equal across the groups.
My questions :
1)- I know we can't choose Hotelling's Trace concerning F test but I read that Wilk's Lambda is the best choice even if Pillai's Trace is more powerful. But I don't know why we shouldn't choose Pillai's Trace or Roy's Largest Root F test?
2)- Concerning Post hoc test, I read that the best test for "Equal Variances Assumed" is Tukey, and for ""Equal Variances not Assumed" is Games-Howell. Why?
3)- I did the Brown-Forsythe and Welch's F test concerning anxiety :
]http://img11.hostingpics.net/pics/12804721AS.jpg
I read that "there is highly significant difference is anxiety scores across pet type " and I don't understand why?
and that "The violation of homogeneity of variances poses no threat to the validity of our results" I don't undestand why?
Thanks in advance
