1. ## Regression (Cubic and Quadratic)

Hi there,

I am trying to run some regression analysis on a dataset I have but have very limited knowledge of Proc Reg. (i.e)

y = x

I have done the straight forward regaression, and have converted the variables of interest to the log(variable) and re ran the analysis.

(i.e)
log(y) = log(x)

I know want to do cubic and quadratic regression.

For cubic am I write in using the formula:
y = x x*x or should it just be y=x*x?

Additionally can anyone help me with how I shoud attempt the quadratic regression?

Sorry I am very much a novice at regression, so if I've made mistakes with my formulas above apologies.

2. ## Re: Regression (Cubic and Quadratic)

A quadratic regression would have 2nd-degree terms, and you should (at least initially) include all lower degree terms.
So the quadratic regression would be: y = x x*x
(ie what you called cubic in your post)

The cubic regression would be: y = x x*x x*x*x

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