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pracolas

Community Trekker

Joined:

Jun 23, 2011

How to show differences between two correlation lines?

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?

http://i55.tinypic.com/awdx80.png

thank you

Message was edited by: pracolas
1 REPLY
ms

Super User

Joined:

Jun 23, 2011

Re: How to show differences between two correlation lines?

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.