# How is R-square calculated in curve fitting tool for LAR and bisqaure robust fit option?

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I find that for a polynomial fit with Bisquare or LAR robust fit option, the r-square value I calculate doesn't match with the curve fitting tool result. does the curve fitting tool use a different formulation than the one explained in here?

please help.

##### 2 Comments

Rik
on 20 Dec 2019

### Answers (1)

ME
on 20 Dec 2019

Does this link help at all?

It looks like LAR doesn't so much minimise an R^2 value but rather minimises the absolute differences. Could that be your issue and why they don't match?

##### 1 Comment

Junxi Zhang
on 3 Feb 2020

LAR minimize the absolute differences, so the fitted model using LAR has different coefficients. That's easy to understand.

However, if we use function "fit" with LAR in command line as well as app "curve fitting tool", the coefficients are the same but the goodness of fit is different. That is to say, SSE, R-sqaure and RMSE are much better in app "curve fitting tool" than in function "fit", which is the same as values calculated manually.

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