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Math Help - Restraining quadratic equation to positive coefficients

  1. #1
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    Restraining quadratic equation to positive coefficients

    Hi,

    I am a postgraduate student carrying out air quality research for my thesis. I have determined a best fit quadratic equation with a zero intercept (y = 1.1133x2 0.0844x) using OLS regression analysis (MS Excel 2013) for a small dataset. As you can see, this has resulted in a negative linear coefficient which raises some difficulties with physical constants that cannot be less than zero. I need to rerun the regression fit with the constraint that both coefficients have to be ≥0 (i.e. positive), retaining the zero intercept, and have been advised that this is possible using MS Excel Solver. Sadly I cannot see how to achieve this. The only other statistical packages I have access to are Minitab (v16) or the openair package in R. Any ideas?

    PS Apologies if I have posted to the wrong forum - I am a complete rookie at this game and more than happy to accept redirection.

    Many thanks
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  2. #2
    MHF Contributor
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    Re: Restraining quadratic equation to positive coefficients

    I'm reading that in Excel you can't use the regression formulas directly but must use the Solver to constrain your regression coefficients.

    This may be helpful.
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