Median of Rayleigh Distribution

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I am not sure how to solve the following problem:



The probability density function of the Rayleigh distribution is,



$ f(x;α) = fracxα^2 e^frac-x^22α^2, x ≥ 0, $



where α is the scale parameter of the distribution. Find the median of the Rayleigh distribution.



I need to derive the median of the distribution, but do not know how to do so. Thoughts?



Thanks!










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    up vote
    1
    down vote

    favorite












    I am not sure how to solve the following problem:



    The probability density function of the Rayleigh distribution is,



    $ f(x;α) = fracxα^2 e^frac-x^22α^2, x ≥ 0, $



    where α is the scale parameter of the distribution. Find the median of the Rayleigh distribution.



    I need to derive the median of the distribution, but do not know how to do so. Thoughts?



    Thanks!










    share|cite|improve this question

























      up vote
      1
      down vote

      favorite









      up vote
      1
      down vote

      favorite











      I am not sure how to solve the following problem:



      The probability density function of the Rayleigh distribution is,



      $ f(x;α) = fracxα^2 e^frac-x^22α^2, x ≥ 0, $



      where α is the scale parameter of the distribution. Find the median of the Rayleigh distribution.



      I need to derive the median of the distribution, but do not know how to do so. Thoughts?



      Thanks!










      share|cite|improve this question















      I am not sure how to solve the following problem:



      The probability density function of the Rayleigh distribution is,



      $ f(x;α) = fracxα^2 e^frac-x^22α^2, x ≥ 0, $



      where α is the scale parameter of the distribution. Find the median of the Rayleigh distribution.



      I need to derive the median of the distribution, but do not know how to do so. Thoughts?



      Thanks!







      pdf median rayleigh






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      edited 1 hour ago

























      asked 1 hour ago









      Joe Ademo

      254




      254




















          1 Answer
          1






          active

          oldest

          votes

















          up vote
          3
          down vote



          accepted










          The Rayleigh distribution has cumulative distribution function (CDF) $F_X(x) = 1-texte^frac-x^22alpha^2$.



          Denote the median $q_50$.



          Starting with the CDF...



          $$beginalign
          1-texte^frac-q_50^22alpha^2 &= 0.5 \
          texte^frac-q_50^22alpha^2 &= 0.5 \
          frac-q_50^22alpha^2 &= textln(0.5) \
          -q_50^2 &= 2alpha^2 textln(0.5) \
          \
          q_50 &=alpha sqrt-2 textln(0.5) \
          &= alpha sqrt2textln(2) quad quad square
          endalign$$






          share|cite|improve this answer




















          • Right, because this is a CRV I should use the CDF. Thanks!!
            – Joe Ademo
            1 hour ago










          • Discrete random variables also have a CDF. I would rather you say since the median (50th-quantile) is an inverse of the CDF, it makes sense to start with the CDF and simply invert. That's how I think about this problem at least.
            – SecretAgentMan
            1 hour ago










          • My point was that since this is a CRV, it would be incorrect to use the PMF. However, I understand your point. Thanks for the help.
            – Joe Ademo
            56 mins ago










          • You could use the density, especially if you love integration by parts... Solve the equation $int_0^q_50 f_X(x)dx = 0.5$.
            – SecretAgentMan
            44 mins ago











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          1 Answer
          1






          active

          oldest

          votes








          1 Answer
          1






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes








          up vote
          3
          down vote



          accepted










          The Rayleigh distribution has cumulative distribution function (CDF) $F_X(x) = 1-texte^frac-x^22alpha^2$.



          Denote the median $q_50$.



          Starting with the CDF...



          $$beginalign
          1-texte^frac-q_50^22alpha^2 &= 0.5 \
          texte^frac-q_50^22alpha^2 &= 0.5 \
          frac-q_50^22alpha^2 &= textln(0.5) \
          -q_50^2 &= 2alpha^2 textln(0.5) \
          \
          q_50 &=alpha sqrt-2 textln(0.5) \
          &= alpha sqrt2textln(2) quad quad square
          endalign$$






          share|cite|improve this answer




















          • Right, because this is a CRV I should use the CDF. Thanks!!
            – Joe Ademo
            1 hour ago










          • Discrete random variables also have a CDF. I would rather you say since the median (50th-quantile) is an inverse of the CDF, it makes sense to start with the CDF and simply invert. That's how I think about this problem at least.
            – SecretAgentMan
            1 hour ago










          • My point was that since this is a CRV, it would be incorrect to use the PMF. However, I understand your point. Thanks for the help.
            – Joe Ademo
            56 mins ago










          • You could use the density, especially if you love integration by parts... Solve the equation $int_0^q_50 f_X(x)dx = 0.5$.
            – SecretAgentMan
            44 mins ago















          up vote
          3
          down vote



          accepted










          The Rayleigh distribution has cumulative distribution function (CDF) $F_X(x) = 1-texte^frac-x^22alpha^2$.



          Denote the median $q_50$.



          Starting with the CDF...



          $$beginalign
          1-texte^frac-q_50^22alpha^2 &= 0.5 \
          texte^frac-q_50^22alpha^2 &= 0.5 \
          frac-q_50^22alpha^2 &= textln(0.5) \
          -q_50^2 &= 2alpha^2 textln(0.5) \
          \
          q_50 &=alpha sqrt-2 textln(0.5) \
          &= alpha sqrt2textln(2) quad quad square
          endalign$$






          share|cite|improve this answer




















          • Right, because this is a CRV I should use the CDF. Thanks!!
            – Joe Ademo
            1 hour ago










          • Discrete random variables also have a CDF. I would rather you say since the median (50th-quantile) is an inverse of the CDF, it makes sense to start with the CDF and simply invert. That's how I think about this problem at least.
            – SecretAgentMan
            1 hour ago










          • My point was that since this is a CRV, it would be incorrect to use the PMF. However, I understand your point. Thanks for the help.
            – Joe Ademo
            56 mins ago










          • You could use the density, especially if you love integration by parts... Solve the equation $int_0^q_50 f_X(x)dx = 0.5$.
            – SecretAgentMan
            44 mins ago













          up vote
          3
          down vote



          accepted







          up vote
          3
          down vote



          accepted






          The Rayleigh distribution has cumulative distribution function (CDF) $F_X(x) = 1-texte^frac-x^22alpha^2$.



          Denote the median $q_50$.



          Starting with the CDF...



          $$beginalign
          1-texte^frac-q_50^22alpha^2 &= 0.5 \
          texte^frac-q_50^22alpha^2 &= 0.5 \
          frac-q_50^22alpha^2 &= textln(0.5) \
          -q_50^2 &= 2alpha^2 textln(0.5) \
          \
          q_50 &=alpha sqrt-2 textln(0.5) \
          &= alpha sqrt2textln(2) quad quad square
          endalign$$






          share|cite|improve this answer












          The Rayleigh distribution has cumulative distribution function (CDF) $F_X(x) = 1-texte^frac-x^22alpha^2$.



          Denote the median $q_50$.



          Starting with the CDF...



          $$beginalign
          1-texte^frac-q_50^22alpha^2 &= 0.5 \
          texte^frac-q_50^22alpha^2 &= 0.5 \
          frac-q_50^22alpha^2 &= textln(0.5) \
          -q_50^2 &= 2alpha^2 textln(0.5) \
          \
          q_50 &=alpha sqrt-2 textln(0.5) \
          &= alpha sqrt2textln(2) quad quad square
          endalign$$







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered 1 hour ago









          SecretAgentMan

          610121




          610121











          • Right, because this is a CRV I should use the CDF. Thanks!!
            – Joe Ademo
            1 hour ago










          • Discrete random variables also have a CDF. I would rather you say since the median (50th-quantile) is an inverse of the CDF, it makes sense to start with the CDF and simply invert. That's how I think about this problem at least.
            – SecretAgentMan
            1 hour ago










          • My point was that since this is a CRV, it would be incorrect to use the PMF. However, I understand your point. Thanks for the help.
            – Joe Ademo
            56 mins ago










          • You could use the density, especially if you love integration by parts... Solve the equation $int_0^q_50 f_X(x)dx = 0.5$.
            – SecretAgentMan
            44 mins ago

















          • Right, because this is a CRV I should use the CDF. Thanks!!
            – Joe Ademo
            1 hour ago










          • Discrete random variables also have a CDF. I would rather you say since the median (50th-quantile) is an inverse of the CDF, it makes sense to start with the CDF and simply invert. That's how I think about this problem at least.
            – SecretAgentMan
            1 hour ago










          • My point was that since this is a CRV, it would be incorrect to use the PMF. However, I understand your point. Thanks for the help.
            – Joe Ademo
            56 mins ago










          • You could use the density, especially if you love integration by parts... Solve the equation $int_0^q_50 f_X(x)dx = 0.5$.
            – SecretAgentMan
            44 mins ago
















          Right, because this is a CRV I should use the CDF. Thanks!!
          – Joe Ademo
          1 hour ago




          Right, because this is a CRV I should use the CDF. Thanks!!
          – Joe Ademo
          1 hour ago












          Discrete random variables also have a CDF. I would rather you say since the median (50th-quantile) is an inverse of the CDF, it makes sense to start with the CDF and simply invert. That's how I think about this problem at least.
          – SecretAgentMan
          1 hour ago




          Discrete random variables also have a CDF. I would rather you say since the median (50th-quantile) is an inverse of the CDF, it makes sense to start with the CDF and simply invert. That's how I think about this problem at least.
          – SecretAgentMan
          1 hour ago












          My point was that since this is a CRV, it would be incorrect to use the PMF. However, I understand your point. Thanks for the help.
          – Joe Ademo
          56 mins ago




          My point was that since this is a CRV, it would be incorrect to use the PMF. However, I understand your point. Thanks for the help.
          – Joe Ademo
          56 mins ago












          You could use the density, especially if you love integration by parts... Solve the equation $int_0^q_50 f_X(x)dx = 0.5$.
          – SecretAgentMan
          44 mins ago





          You could use the density, especially if you love integration by parts... Solve the equation $int_0^q_50 f_X(x)dx = 0.5$.
          – SecretAgentMan
          44 mins ago


















           

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