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The effect of coding on Sxx/Syy/Sxy?

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    What is the effect of coding data on the values of Sxx, Sxy and Syy. I realise r just remains the same. This is for statistics S1
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    You're not getting much response - so I'll take a stab at this.

    If you add a fixed amount to either the x or y values you will not affect any of Sxx Sxy or Syy because they all subtract the mean.

    If you multiply the x values by say 2 you will quadruple the Sxx value, double the Sxy value and not change the Syy value.
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    (Original post by ian.slater)
    You're not getting much response - so I'll take a stab at this.

    If you add a fixed amount to either the x or y values you will not affect any of Sxx Sxy or Syy because they all subtract the mean.

    If you multiply the x values by say 2 you will quadruple the Sxx value, double the Sxy value and not change the Syy value.
    So it's like variance then; in saying that Var(2X+5)=22Var(X) in the case of Sxx and then for Sxy it's like standard deviation (presumably because the x value isn't squared in an Sxy calculation).

    Thanks for responding
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    (Original post by the.austrian)
    So it's like variance then; in saying that Var(2X+5)=22Var(X) in the case of Sxx and then for Sxy it's like standard deviation (presumably because the x value isn't squared in an Sxy calculation).

    Thanks for responding
    Yes, exactly the same, make sure you square it as you've said
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    So if you are multiplying x by 9, would Sxx be multiplied by 81??
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    (Original post by Ellieseftel)
    So if you are multiplying x by 9, would Sxx be multiplied by 81??
    You catch on fast
Updated: June 11, 2016
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