Simpson’s Paradox: which relationship is more “true” the aggregate or the groups?

Hello,

I am doing an analysis using linear regression where I have 3 variables. I have 6 categories, an independent and dependent variable. There are 120 samples, so I have 6 groups of 20 samples.

What I found is when I compute the line of best fit for the groups, they all have a negative relationship. But when I compute the line of best for the aggregate data, the relationship is positive. Also all of the group and the aggregate …

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