Is there a possibility that $|Corr(X,Y)|=1$ and there's no linear relationship between them?











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Let us have $|Corr(X,Y)|=1$.



When is it possible for the variables $X,Y$ not be linearly related?



I would say that they must have infinite moments... But I'm not seeing if that's enough to get the result I want.










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    up vote
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    down vote

    favorite












    Let us have $|Corr(X,Y)|=1$.



    When is it possible for the variables $X,Y$ not be linearly related?



    I would say that they must have infinite moments... But I'm not seeing if that's enough to get the result I want.










    share|cite|improve this question
























      up vote
      0
      down vote

      favorite









      up vote
      0
      down vote

      favorite











      Let us have $|Corr(X,Y)|=1$.



      When is it possible for the variables $X,Y$ not be linearly related?



      I would say that they must have infinite moments... But I'm not seeing if that's enough to get the result I want.










      share|cite|improve this question













      Let us have $|Corr(X,Y)|=1$.



      When is it possible for the variables $X,Y$ not be linearly related?



      I would say that they must have infinite moments... But I'm not seeing if that's enough to get the result I want.







      probability






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      asked Nov 16 at 20:37









      An old man in the sea.

      1,60411031




      1,60411031






















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          By the Cauchy-Schwarz inequality, $X$ is a constant multiple of $Y$ in this case.






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          • We can use Cauchy-Schwarz only if we have $E(XY)$ finite.
            – An old man in the sea.
            Nov 16 at 20:52










          • We can have $operatorname{Corr}(XY)$ only if $E(XY)$, $E(X^2)$, and $E(Y^2)$ are all finite.
            – kimchi lover
            Nov 16 at 21:03











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          1 Answer
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          active

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          up vote
          1
          down vote













          By the Cauchy-Schwarz inequality, $X$ is a constant multiple of $Y$ in this case.






          share|cite|improve this answer





















          • We can use Cauchy-Schwarz only if we have $E(XY)$ finite.
            – An old man in the sea.
            Nov 16 at 20:52










          • We can have $operatorname{Corr}(XY)$ only if $E(XY)$, $E(X^2)$, and $E(Y^2)$ are all finite.
            – kimchi lover
            Nov 16 at 21:03















          up vote
          1
          down vote













          By the Cauchy-Schwarz inequality, $X$ is a constant multiple of $Y$ in this case.






          share|cite|improve this answer





















          • We can use Cauchy-Schwarz only if we have $E(XY)$ finite.
            – An old man in the sea.
            Nov 16 at 20:52










          • We can have $operatorname{Corr}(XY)$ only if $E(XY)$, $E(X^2)$, and $E(Y^2)$ are all finite.
            – kimchi lover
            Nov 16 at 21:03













          up vote
          1
          down vote










          up vote
          1
          down vote









          By the Cauchy-Schwarz inequality, $X$ is a constant multiple of $Y$ in this case.






          share|cite|improve this answer












          By the Cauchy-Schwarz inequality, $X$ is a constant multiple of $Y$ in this case.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Nov 16 at 20:43









          Mike Hawk

          1,312110




          1,312110












          • We can use Cauchy-Schwarz only if we have $E(XY)$ finite.
            – An old man in the sea.
            Nov 16 at 20:52










          • We can have $operatorname{Corr}(XY)$ only if $E(XY)$, $E(X^2)$, and $E(Y^2)$ are all finite.
            – kimchi lover
            Nov 16 at 21:03


















          • We can use Cauchy-Schwarz only if we have $E(XY)$ finite.
            – An old man in the sea.
            Nov 16 at 20:52










          • We can have $operatorname{Corr}(XY)$ only if $E(XY)$, $E(X^2)$, and $E(Y^2)$ are all finite.
            – kimchi lover
            Nov 16 at 21:03
















          We can use Cauchy-Schwarz only if we have $E(XY)$ finite.
          – An old man in the sea.
          Nov 16 at 20:52




          We can use Cauchy-Schwarz only if we have $E(XY)$ finite.
          – An old man in the sea.
          Nov 16 at 20:52












          We can have $operatorname{Corr}(XY)$ only if $E(XY)$, $E(X^2)$, and $E(Y^2)$ are all finite.
          – kimchi lover
          Nov 16 at 21:03




          We can have $operatorname{Corr}(XY)$ only if $E(XY)$, $E(X^2)$, and $E(Y^2)$ are all finite.
          – kimchi lover
          Nov 16 at 21:03


















           

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