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Carry out a simulation experiment using a statistical computer package or other software to study the sampling distribution of \({\rm{\bar X}}\) when the population distribution is lognormal with \({\rm{E(ln(X)) = 3}}\) and\({\rm{V(ln(X)) = 1}}\). Consider the four sample sizes\({\rm{n = 10,20,30}}\), and\({\rm{50}}\), and in each case use \({\rm{1000}}\) replications. For which of these sample sizes does the \({\rm{\bar X}}\) sampling distribution appear to be approximately normal?

Short Answer

Expert verified

The last histogram and normal probability plot are for sample size\({\rm{n = 300}}\), mainly to show that the sample distribution becomes closer to normal as \({\rm{n}}\) rises.

Step by step solution

01

Definition

Probability simply refers to the likelihood of something occurring. We may talk about the probabilities of particular outcomes鈥攈ow likely they are鈥攚hen we're unclear about the result of an event. Statistics is the study of occurrences guided by probability.

02

Determining the sample size

Simulate the sample distribution of \({\rm{\bar X}}\) using any programmed, such as \({\rm{R}}\), math lab, python, or a statistical computer package, given a lognormal distribution with expectation \({\rm{3}}\) and variance\({\rm{1}}\).

Calculate the mean for each sample first. A histogram and a normal probability plot should be plotted. The distribution tends to be normal as \({\rm{n}}\) rises; nevertheless, as the histograms and normal probability plots below show, the distribution is not roughly normal for given sample sizes. The last histogram and normal probability plot are for sample size\({\rm{n = 300}}\), mainly to show that the sample distribution becomes closer to normal as \({\rm{n}}\) rises.

For\({\rm{n = 10}}\), the following are histogram and normal probability plot:

03

Determining the sample size

\({\rm{ For n = 20, the following are histogram and normal probability plot: }}\)

04

Determining the sample size

\({\rm{ For n = 30, the following are histogram and normal probability plot: }}\)

05

Determining the sample size

\({\rm{ For n = 50, the following are histogram and normal probability plot: }}\)

06

Determining the sample size

\({\rm{ For n = 300, the following are histogram and normal probability plot: }}\)

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