An Integration problem of Bivariate Normal Distribution












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I'm currently solving previous years problems for my M.Sc Statistics entrance exam on IIT (India).



Problem->



Find the value of



$$frac{1}{2pi}int_{-infty}^{infty}int_{-infty}^y e^{frac{-1}{2}(x^2 + y^2)}mathop{dx} mathop{dy}$$



This is a PDF of Bivariate Normal(0,0,1,1,cor=0)
Now I can't find an right approach to solve it, I tried integrating but it became messed up as after using the integration by parts form. Thank you for your time :-)










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  • $begingroup$
    If you can use that this is circularly symmetric and a distribution, then you may exploit the symmetry, right? A distribution adds up to 1, it is divided into two symmetrical parts, each part shall add up to 0.5? If you wish to deal with the double integral typical approach would be making the exponent square.
    $endgroup$
    – keoxkeox
    Jan 23 at 8:27












  • $begingroup$
    This has been asked before but I cannot find the question.
    $endgroup$
    – StubbornAtom
    Jan 23 at 8:38










  • $begingroup$
    Here's one: math.stackexchange.com/questions/2675055/….
    $endgroup$
    – StubbornAtom
    Jan 23 at 10:51
















0












$begingroup$


I'm currently solving previous years problems for my M.Sc Statistics entrance exam on IIT (India).



Problem->



Find the value of



$$frac{1}{2pi}int_{-infty}^{infty}int_{-infty}^y e^{frac{-1}{2}(x^2 + y^2)}mathop{dx} mathop{dy}$$



This is a PDF of Bivariate Normal(0,0,1,1,cor=0)
Now I can't find an right approach to solve it, I tried integrating but it became messed up as after using the integration by parts form. Thank you for your time :-)










share|cite|improve this question











$endgroup$












  • $begingroup$
    If you can use that this is circularly symmetric and a distribution, then you may exploit the symmetry, right? A distribution adds up to 1, it is divided into two symmetrical parts, each part shall add up to 0.5? If you wish to deal with the double integral typical approach would be making the exponent square.
    $endgroup$
    – keoxkeox
    Jan 23 at 8:27












  • $begingroup$
    This has been asked before but I cannot find the question.
    $endgroup$
    – StubbornAtom
    Jan 23 at 8:38










  • $begingroup$
    Here's one: math.stackexchange.com/questions/2675055/….
    $endgroup$
    – StubbornAtom
    Jan 23 at 10:51














0












0








0





$begingroup$


I'm currently solving previous years problems for my M.Sc Statistics entrance exam on IIT (India).



Problem->



Find the value of



$$frac{1}{2pi}int_{-infty}^{infty}int_{-infty}^y e^{frac{-1}{2}(x^2 + y^2)}mathop{dx} mathop{dy}$$



This is a PDF of Bivariate Normal(0,0,1,1,cor=0)
Now I can't find an right approach to solve it, I tried integrating but it became messed up as after using the integration by parts form. Thank you for your time :-)










share|cite|improve this question











$endgroup$




I'm currently solving previous years problems for my M.Sc Statistics entrance exam on IIT (India).



Problem->



Find the value of



$$frac{1}{2pi}int_{-infty}^{infty}int_{-infty}^y e^{frac{-1}{2}(x^2 + y^2)}mathop{dx} mathop{dy}$$



This is a PDF of Bivariate Normal(0,0,1,1,cor=0)
Now I can't find an right approach to solve it, I tried integrating but it became messed up as after using the integration by parts form. Thank you for your time :-)







integration






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share|cite|improve this question













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edited Jan 23 at 9:45









Paras Khosla

1,826219




1,826219










asked Jan 23 at 7:42









user194259user194259

305




305












  • $begingroup$
    If you can use that this is circularly symmetric and a distribution, then you may exploit the symmetry, right? A distribution adds up to 1, it is divided into two symmetrical parts, each part shall add up to 0.5? If you wish to deal with the double integral typical approach would be making the exponent square.
    $endgroup$
    – keoxkeox
    Jan 23 at 8:27












  • $begingroup$
    This has been asked before but I cannot find the question.
    $endgroup$
    – StubbornAtom
    Jan 23 at 8:38










  • $begingroup$
    Here's one: math.stackexchange.com/questions/2675055/….
    $endgroup$
    – StubbornAtom
    Jan 23 at 10:51


















  • $begingroup$
    If you can use that this is circularly symmetric and a distribution, then you may exploit the symmetry, right? A distribution adds up to 1, it is divided into two symmetrical parts, each part shall add up to 0.5? If you wish to deal with the double integral typical approach would be making the exponent square.
    $endgroup$
    – keoxkeox
    Jan 23 at 8:27












  • $begingroup$
    This has been asked before but I cannot find the question.
    $endgroup$
    – StubbornAtom
    Jan 23 at 8:38










  • $begingroup$
    Here's one: math.stackexchange.com/questions/2675055/….
    $endgroup$
    – StubbornAtom
    Jan 23 at 10:51
















$begingroup$
If you can use that this is circularly symmetric and a distribution, then you may exploit the symmetry, right? A distribution adds up to 1, it is divided into two symmetrical parts, each part shall add up to 0.5? If you wish to deal with the double integral typical approach would be making the exponent square.
$endgroup$
– keoxkeox
Jan 23 at 8:27






$begingroup$
If you can use that this is circularly symmetric and a distribution, then you may exploit the symmetry, right? A distribution adds up to 1, it is divided into two symmetrical parts, each part shall add up to 0.5? If you wish to deal with the double integral typical approach would be making the exponent square.
$endgroup$
– keoxkeox
Jan 23 at 8:27














$begingroup$
This has been asked before but I cannot find the question.
$endgroup$
– StubbornAtom
Jan 23 at 8:38




$begingroup$
This has been asked before but I cannot find the question.
$endgroup$
– StubbornAtom
Jan 23 at 8:38












$begingroup$
Here's one: math.stackexchange.com/questions/2675055/….
$endgroup$
– StubbornAtom
Jan 23 at 10:51




$begingroup$
Here's one: math.stackexchange.com/questions/2675055/….
$endgroup$
– StubbornAtom
Jan 23 at 10:51










1 Answer
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Your integral is $int_{(x,,y)inBbb R^2land xle y}phi(x)phi(y)dxdy$, with $phi$ the $N(0,,1)$ pdf. Therefore, it is the probability $xle y$ subject to $x,,y$ being $N(0,,1)$ iids. In other words, $1/2$.






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    1 Answer
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    $begingroup$

    Your integral is $int_{(x,,y)inBbb R^2land xle y}phi(x)phi(y)dxdy$, with $phi$ the $N(0,,1)$ pdf. Therefore, it is the probability $xle y$ subject to $x,,y$ being $N(0,,1)$ iids. In other words, $1/2$.






    share|cite|improve this answer









    $endgroup$


















      0












      $begingroup$

      Your integral is $int_{(x,,y)inBbb R^2land xle y}phi(x)phi(y)dxdy$, with $phi$ the $N(0,,1)$ pdf. Therefore, it is the probability $xle y$ subject to $x,,y$ being $N(0,,1)$ iids. In other words, $1/2$.






      share|cite|improve this answer









      $endgroup$
















        0












        0








        0





        $begingroup$

        Your integral is $int_{(x,,y)inBbb R^2land xle y}phi(x)phi(y)dxdy$, with $phi$ the $N(0,,1)$ pdf. Therefore, it is the probability $xle y$ subject to $x,,y$ being $N(0,,1)$ iids. In other words, $1/2$.






        share|cite|improve this answer









        $endgroup$



        Your integral is $int_{(x,,y)inBbb R^2land xle y}phi(x)phi(y)dxdy$, with $phi$ the $N(0,,1)$ pdf. Therefore, it is the probability $xle y$ subject to $x,,y$ being $N(0,,1)$ iids. In other words, $1/2$.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Jan 23 at 10:58









        J.G.J.G.

        29.8k22947




        29.8k22947






























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