MANOVA vs multiple ANOVAs

Laf

New Member
#1
Hello,

I have 3 variables that have been measured on 4 occasions and a sample size of 16. I was considering a repeated measures MANOVA to ascertain if the changes over time were statistically significant. However, I am thinking that my sample size is too small to use a MANOVA in this way. I am considering using 3 separate repeated measures ANOVAs (one for each variable) instead. Just wondering if this is acceptable and/or justifiable.

Thank you,
Laf
 

Karabiner

TS Contributor
#2
In three seperate ANOVAs your sample would still be small.
Why do you think you shouldn't do a repeated measures analysis
with n=16?

Kind regards

K.
 

Laf

New Member
#3
Thanks for the response. My main concern re using a MANOVA was lack of power. I used G*Power, and it indicated that I should have a sample size of 48 to detect a small effect size. The repeated measures ANOVA was better - said I needed half has much. I know I'm still short, but I thought it was the better/safer option given the circumstances. What do you think?
 

Karabiner

TS Contributor
#4
I am not sure whether the respective power analyses were
performed perfectely correct. With 12 measurements I would
expect a repeated measures analysis to have more power
than with 4 measurements.

Kind regards

K.