How can I perform a linear regression analysis with the equation y=a(x-b)?

Hi

I am new to MATLAB.

I don't have access to the statistics toolbox but I would like to perform a linear regression on my data but I need the x intercept (and standard error of the intercept) so need to use the linear equation in the form y=a(x-b) rather than y=ax+b. If I could get the r squared value for the fit too that would be great.

Thanks for your help Gavin

Answer 1

[Honglei Chen]

This is essentially the same as fitting y=ax+b since it can be written as y=ax+b=a(x-(-b/a)). So all you need to do is to fit y=ax+b and then do the conversion. You can use polyfit to do the fit of y=ax+b.

http://www.mathworks.com/help/techdoc/ref/polyfit.html

Answer 2

[per isakson]

Search for "basic fitting" in the on-line documentation. I think that includes all what you need.

Or see: http://www.mathworks.se/help/techdoc/data_analysis/f1-15377.html#f1-15488