# [R] How to fit a linear model to data by minimizing the mean absolute percent error?

Jeff Newmiller jdnewmil at dcn.davis.CA.us
Mon Jan 14 16:46:30 CET 2013

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Sent from my phone. Please excuse my brevity.

Andre Cesta <aacesta at yahoo.com> wrote:

>
>
>Hi All, I wonder if you can help me with an aparently simple task.  I
>have been searching examples for this without any luck: #Assume
>x<-1:10  #x ranges from 1 to 10.
>y<-x*runif(10)+ 1.5*x  #y is a linear function of x with some error.
>Add uniform error that is scaled to be larger as x values also become
>larger #error is proportional to x size, this should cause
>heterocedasticity. #I know there are many methods to deal with
>heterocedasticity, but in my specific case, I want to use percent
>regression to minimize the mean absolute
>#percentual error as opposed to regular regression that deals with the
>square of the errors. #Question, how to fit a linear model to minimize
>this error on the data y ~ x above?
>#Please do not use model<-lm(y ~ x....) as this will minimize the
>square of the errors, not the mean absolute percent error Best regards,
>André Cesta
>
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