Chunk #16 — Methods and results — Delineation of the problem

Source

Testing for measured gene-environment interaction: problems with the use of cross-product terms and a regression model reparameterization solution.

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yes

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Another problem is that all three lines must cross at the same point or all must be parallel depending on the β3 coefficient. When β3 = 0 all three lines have the same slopes equal to β2. This means that all lines are parallel. When β3 ≠ 0 all three lines cross at the same point. To find the crossing point of two lines we equate the equations. Equating the first and second lines we get β0+β2E=(β0+β1)+(β2+β3)E.