non-linear models

[carlacoga325]

hi im working on the relationship between inflation and unemployment to explain the non-linear models topic. I want to use a regression from eveiws but i dont know how to do a polinomial regression starting from the data or if it is necesary to express the ecuation in a linear form first?
Also, if i start with a lineal regression is there some test to identify whether a non linear regression would be more adequate or is the scatter analysis sufficient?
thnx!

[startz]

hi im working on the relationship between inflation and unemployment to explain the non-linear models topic. I want to use a regression from eveiws but i dont know how to do a polinomial regression starting from the data or if it is necesary to express the ecuation in a linear form first?
Also, if i start with a lineal regression is there some test to identify whether a non linear regression would be more adequate or is the scatter analysis sufficient?
thnx!

A polynomial regression is easy

Code: Select all

ls y c x x^2 x^3 x^4

You can always test if the coefficients on the higher order terms are jointly significant.

[carlacoga325]

thanx i did that and it worked, im only having trouble cuz it accepts the expression ln but not log...so it wont accept the expression y =(-0.7)ln(x) + 2.5872 and also for example when i put there the expression y =(2356.1)x^2 - (165.37)x + 7.6965 it doesnt do it becuause of things like "= is not defined".

thank u so much for your help :D

[EViews Gareth]

You might want to rephrase that question so that it makes sense.

[startz]

I can't understand what you're doing. (And if Gareth can't understand, you're really unclear. ) Perhaps you can explain more slowly, posting exactly what you've done and what you are hoping to accomplish.

[samijo]

I guess you need to use the multiplication sigh so the expression looks like y =(-0.7)*ln(x) + 2.5872.
So in the command line you might type
ls y c ln(x)
ls y c x x^2
I don't find any problem with the ln and log function, however, you should notice that log(x) and ln(x) give the natural log. In order to get the log to the base 10 you need to use log10(x).