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Math 6010 • Linear Models

Spring 2008 • Question 7

Let \(X_1,X_2,\ldots \) be i.i.d. mean 0, variance 1 random variables and \(S_n=X_1+\cdots +X_n\) for each \(n\geq 1\). Show directly that the characteristic function of \(S_n/\sqrt {n}\) converges pointwise to the characteristic function of the standard normal distribution. Notice that this is a key step in the proof of the central limit theorem, so you are not allowed to use the central limit theorem in your derivation.

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Let \(X_1,X_2,\ldots\) be i.i.d. mean 0, variance 1 random variables
and \(S_n=X_1+\cdots+X_n\) for each \(n\geq1\). Show directly that the
characteristic function of \(S_n/\sqrt{n}\) converges pointwise to the
characteristic function of the standard normal distribution. Notice that this is
a key step in the proof of the central limit theorem, so you are \emph{not}
allowed to use the central limit theorem in your derivation.