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How to show differences between two correlation lines?


Community Trekker


Jun 23, 2011

Hi guys,
here is my daily newbee question:

I have a bivaried analyse between Amax and BC with two groups. I grouped the data and made 2 correlation lines.

Now, how can I show that Amax is significantly Higher in the red group than in the blue group?

thank you

Message was edited by: pracolas

Super User


Jun 23, 2011

Use the Fit Model platform. Enter Amax as Y. Select BC and the nominal grouping column and choose "Full Factorial" in the Macros drop-down menu. Then you get a model with one nominal and one continuous independent variable plus their interaction (often called ANCOVA).

In the report, look in the "Effect Tests" table box. If the p-value for the grouping column is low (e.g. <0.05) the groups differ. If the BC p-value is low, BC has a significant (linear) relationship with Amax, and finally, if the interaction term p-value is low, the Amax-BC slopes are significantly different between the two groups.