Math Is Fun Forum

lindah

Member

Registered: 2010-01-25

Posts: 121

Regression: Transformed variables

Hi guys,

I have a dilemma about a log-transformed regression

And so the transformation is

Assuming I have found the coefficient parameters for

and

, I am required to test the hypothesis that

by building the 95% confidence interval using

and

.

I am unsure about transforming back or keeping the interval. Here is my thinking

1) I use the standard errors of the coefficients of

and

from the regression output and build a confidence interval:

where t - is the critical value

2) Take the exponential to get back to normal scale and if the confidence interval contains 1, then accept the null hypothesis

Would this be the correct procedure?
Some people have said to me that this distorts the standard errors of the coefficient.
I would also like to note that the original data (pre-transformed) has no scale and was just raw numbers

Thanks in advance for any feedback,

Linda

Last edited by lindah (2011-06-02 11:27:16)