domain error power regression

[james schierer]

Looking for help. We are doing power regressions and getting domain errors when the y values are negative. Could I get a reason as to why and does someone have a fix on how to get past this   Thank You James

[Marc Garneau]

I think the regression procedure requires logs, hence the arguments cannot be negative.

So, even though the function y = a*x^b can admit of negative values for x and y, the regression process cannot.

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[Sean Bird]

I don't even think you want to have a value for 0 based on a recent power regression I did. I got the much closer to the expected value for 'b' of -1, when I didn't have a (0,something)
:)
This can be seen in a data collection activity. (Don't make it full screen, since I didn't get it in as focus as I would have liked.)
http://bird-godlydominion.blogspot.com/

- Sean Bird
Covenant Christian High School

[james schierer]

Thanks for the help, I have had the problem with 0 as a value with errors for log regressions so I now know to avoid that.   James --- On Fri, 11/18/11, Sean Bird <covena...@gmail.com> wrote: