Approximating probability of Cumulative Sum of random variables samples from Uniform[-1,1]












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Here is the question:



For $n = 25$ and $50$, approximate the probability $P(max_{1 leq k leq n} S_k > 2sqrt n)$ when the sample observations are iid $U[−1, 1]$, where $S_k= X_1 + X_2+...+X_k$.



I understand that it wants us to approximate the probability that the maximum cumulative sum of the $X_i$s is greater than $2sqrt n$. So, I created a code in R to run the simulation 10000 times and the probability turns out to be very small (i.e 5e-04, 3e-04).



However, I am stuck on how this can be shown by hand. Any help is greatly appreciated!



I also found this theorem in my book that might be related but I am not sure because it has n going to infinity:



$$lim_{nrightarrow infty} P(max_{1 leq k leq n} S_k leq xsqrt n) = G(x), text{ where } G(x)= 2Phi(x)-1. $$










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    1












    $begingroup$


    Here is the question:



    For $n = 25$ and $50$, approximate the probability $P(max_{1 leq k leq n} S_k > 2sqrt n)$ when the sample observations are iid $U[−1, 1]$, where $S_k= X_1 + X_2+...+X_k$.



    I understand that it wants us to approximate the probability that the maximum cumulative sum of the $X_i$s is greater than $2sqrt n$. So, I created a code in R to run the simulation 10000 times and the probability turns out to be very small (i.e 5e-04, 3e-04).



    However, I am stuck on how this can be shown by hand. Any help is greatly appreciated!



    I also found this theorem in my book that might be related but I am not sure because it has n going to infinity:



    $$lim_{nrightarrow infty} P(max_{1 leq k leq n} S_k leq xsqrt n) = G(x), text{ where } G(x)= 2Phi(x)-1. $$










    share|cite|improve this question











    $endgroup$















      1












      1








      1





      $begingroup$


      Here is the question:



      For $n = 25$ and $50$, approximate the probability $P(max_{1 leq k leq n} S_k > 2sqrt n)$ when the sample observations are iid $U[−1, 1]$, where $S_k= X_1 + X_2+...+X_k$.



      I understand that it wants us to approximate the probability that the maximum cumulative sum of the $X_i$s is greater than $2sqrt n$. So, I created a code in R to run the simulation 10000 times and the probability turns out to be very small (i.e 5e-04, 3e-04).



      However, I am stuck on how this can be shown by hand. Any help is greatly appreciated!



      I also found this theorem in my book that might be related but I am not sure because it has n going to infinity:



      $$lim_{nrightarrow infty} P(max_{1 leq k leq n} S_k leq xsqrt n) = G(x), text{ where } G(x)= 2Phi(x)-1. $$










      share|cite|improve this question











      $endgroup$




      Here is the question:



      For $n = 25$ and $50$, approximate the probability $P(max_{1 leq k leq n} S_k > 2sqrt n)$ when the sample observations are iid $U[−1, 1]$, where $S_k= X_1 + X_2+...+X_k$.



      I understand that it wants us to approximate the probability that the maximum cumulative sum of the $X_i$s is greater than $2sqrt n$. So, I created a code in R to run the simulation 10000 times and the probability turns out to be very small (i.e 5e-04, 3e-04).



      However, I am stuck on how this can be shown by hand. Any help is greatly appreciated!



      I also found this theorem in my book that might be related but I am not sure because it has n going to infinity:



      $$lim_{nrightarrow infty} P(max_{1 leq k leq n} S_k leq xsqrt n) = G(x), text{ where } G(x)= 2Phi(x)-1. $$







      probability statistics probability-distributions statistical-inference






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      share|cite|improve this question













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      edited Feb 3 at 9:02









      pointguard0

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      1,57611122










      asked Feb 3 at 2:45









      MBRMBR

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