Help needed with interpretation of a (clear) 2x3-ANOVA interaction

Dear Stats community

I hope someone can help me interpreting my results.

I ran two tests, each with three participant groups. So I have a within-subject factor with 2 levels and a between-subject factor with 3 levels. Interaction is significant.

I attached a picture to show you the data.

How do I proceed from here? Which group caused the interaction?
From the picture I infer, that the red group caused the interaction. I ran three additional repeated-measures-anova for red-green, red-blue, and green-blue comparisons. These tests verified my guess. But I think this is not a legal statistical procedure. How can I statistically find out which of the three groups caused the interaction?
Is it even possible?

I am thankful for any idea or help.
Have a great day


additional information

The x-axis of the picture just shows test 1 and 2. The y-axis shows scores. The lines are the connected performances of the three different groups for test 1 and 2.
In case you can't see the picture: I have three groups: red, green and blue.
red and blue line cross each other, so that red scores higher in test 1 and blue scores higher in test 2. the green line is parallel to the blue one, but on overall lower scores and no crossing with the red line.

First I ran a 2x3 repeated measures anova. Both main effects (groups and tests) were significant. Interaction was significant, too.

Afterwards I ran simple main effects analysis:
For all groups the scores in test 1 and test 2 are significantly different.
For test 2 the scores of the different groups are not significantly different.
For test 1 the scores of the different groups are significantly different.

multiple comparison (bonferroni corrected+) for test 1 showed that the green group scores significantly different from the other two.


Less is more. Stay pure. Stay poor.
Seems like you made the right approaches. As can be seen the slopes are not congruent. Did you have an interaction term in your model? What program are you using?
Hey hlsmith

thanks for the reply. Sorry, but I am not quite sure what you mean by interaction term. I only know it from regression models.

I used SPSS to run a two-way-repeated-measure-ANOVA with a 3 level between-subjects factor and a 2 level within subjects factor. And interaction was significant.
I know I am repeating myself, but maybe you can explain what you mean by interaction term :)

Thank you very much,
I just want to refresh the treat and still hope for some help.
I still don't know exactly what was meant with the interaction term by hlsmith.

Thanks for any hints.