Understanding Mixed ANOVA output

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Vainer
Posts: 1
Joined: Fri Apr 15, 2016 4:56 am

Understanding Mixed ANOVA output

Postby Vainer » Fri Apr 15, 2016 5:21 am

Hey guys!

I've got a question about the output of the mixed ANOVA test -
My study is about the effect of a given drug on the eyes. The right eye is the study group whether the left eye of the same person is the control.
I would like SPSS to tell me the following:
1. Is there any difference between the eyes?
2. Is there any difference between the eyes over time?

The best suitable test for my questions is the mixed ANOVA (as far as I know).
I've attached the output of my statistical analysis here.

When reading the output I've had some hard time understanding many things, so to summarize my thoughts I'll make a list of my conclusions:
1. I have 5 time set points where I made my measurements.
2. I have 2 groups - Left and Right eye.
Moving to the output itself -
3. The Mauchly's Test got a P of 0.002 so I cannot assume Sphericity, and by that have to use one of the corrections (Greenhouse-Geisser etc.)
4. When looking at the Tests of Within-Subjects Effects -
a. Time is significant - so I can say that time has an impact by itself on my measurements and they change with time.
b. Time*Group is also significant, so I can say that there was a difference between the two groups over time.
5. When looking at the Test of Between Subject Effect I can see that Group is not significant (P=0.236) so can I assume here that there is no difference between the groups, although the interaction between time and the group is significant?

If someone would be kind to look at the output I've attached and the conclusion I've made and tell me whether I'm right or wrong? :)

I feel that I didn't interpret the output correctly and would like to learn from my mistakes.

Link to the output file -
https://copy.com/rxnQClfHBcGu674M

A million thanks to you guys!
V
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