Regression-Discontinuity Design - Institute for Policy Research

Adding Nonlinear and Interaction Terms
to the Model
• And one can add both nonlinear and interaction
terms to the model:
Y i
= ˆβ 0
+ ˆβ 1
d i
+ ˆβ 2
(z i
− z c
) + ˆβ 3
(z i
− z c
) 2
+ ˆβ 4
d i
(z i
− z c
) + ˆβ 5
d i
(z i
− z c
) 2 + e i
• As you can imagine, the model can get quite large.
• Though it may seem complex, all this can easily be
done in SPSS, and all the relevant terms can easily be
defined with simple SPSS Compute statements.