1. Supplement on Multiple Regression Interpretation
Module 33 A:
Supplement on Multiple Regression Interpretation
This module expands the discussion of the interpretation of the regression model parameters for the first example in Module 33
Reviewed 19 July 05 / MODULE 33A

4. y = Quality of Well Being score (QWB) at two years  

5. x1: Intervention x1 = 1 if person was in intervention group
= 0 otherwise

6. x2: QWB at baseline
x2 = baseline score

7. x3: Gender
x3 = 1 if person was a male
= 0 otherwise, i.e. a female

8. x4-5: Age x4 = 1 if age 75-84 x5 = 1 if age 85 +
= 0 otherwise = 0 otherwise

9. x6-7: GHQ x6 = 1 if moderate x7 = 1 if severe
= 0 otherwise = 0 otherwise

10. x8: Physically active x8 = 1 if ≥ 3 times per week
= 0 if < three times per week

11. x9: Reduced weight
x9 = 1 if tried to lose weight
= 0 otherwise

12. x10: Medigap (Other insurance)
x10 = 1 if Medigap insurance
= 0 if otherwise, i.e. Medicaid

13. x11: Education
x11 = education level in years

14. x12: Education  Intervention interaction
x12 = (x11) * (x1)
b12 = means that the QWB score at two years decreases units for each year of education for x12 = 1, which is the intervention group. For x12 = 0, the control group, this term is zero.