Sept 2019-Ques 3 iii)

Discussion in 'CS2' started by Actuary@22, Apr 3, 2021.

  1. Actuary@22

    Actuary@22 Very Active Member

    Hello
    Please tell that how the given process i:e the general random walk tends to a normal distribution after large number of time priods.
    Also,how do we then estimate the parameters of the distribution?
     
  2. Julie Lewis

    Julie Lewis Member

    I think you mean the distribution of X(n) is approximately normal for large n. If X is a RW, then:

    X(n) = Z(1) + Z(2) + ... Z(n)

    where Z is white noise, ie the Z's are IID RVs.

    By the Central Limit Theorem, the distribution of a sum of n IID RVs is approx normal with mean n*mu and variance n*sigma^2, provided n is large. Here mu = E(Z) and sigma^2 = var(Z).
     

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