Posts Tagged ‘ normal distribution ’

June Reading List

June 3, 2017
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June Reading List

Here are some suggestions for you:Ai, C. and E. C. Norton, 2003. Interaction terms in logit and probit models. Economics Letters, 80, 123-129.Hirschberg, J. and J. Lye, 2017. Inverting the indirect - the ellipse and the Boomerang: Visualizing the confi...

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February Reading List

February 2, 2016
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February Reading List

Here's a suggested reading list for February:Casey, G. and M. Klemp, 2016. Instrumental variables in the long run. MPRA Paper No. 68696.Coglianese, J., L. W. Davis, L. Kilian, and J. H. Stock, 2016. Anticipation, tax avoidance, and the price elasticity...

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The normal distribution – three tricky bits

January 18, 2016
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The normal distribution – three tricky bits

There are several tricky things about teaching and understanding the normal distribution, and in this post I’m going to talk about three of them. They are the idea of a model, the limitations of the normal distribution, and the idea … Continue reading →

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Why Does "Pi" Appear in the Normal Density

January 16, 2016
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Why Does "Pi" Appear in the Normal Density

Every now and then a student will ask me why the formula for the density of a Normal random variable includes the constant, π, or more correctly (2π)-½.The answer is that this term ensures that the density function is "proper" - that is, the integra...

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a programming bug with weird consequences

November 24, 2015
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a programming bug with weird consequences

One student of mine coded by mistake an independent Metropolis-Hastings algorithm with too small a variance in the proposal when compared with the target variance. Here is the R code of this implementation: It produces outputs of the following shape which is quite amazing because of the small variance. The reason for the lengthy freezes […]

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Illustrating Spurious Regressions

October 2, 2015
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Illustrating Spurious Regressions

I've talked a bit about spurious regressions a bit in some earlier posts (here and here). I was updating an example for my time-series course the other day, and I thought that some readers might find it useful.Let's begin by reviewing what is usually m...

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The Distribution of a Ratio of Correlated Normals

August 25, 2015
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The Distribution of a Ratio of Correlated Normals

Suppose that the random variables X1 and X2 are jointly distributed as bivariate Normal, with means of θ1 and θ2, variances of σ12 and σ22 respectively, and a correlation coefficient of ρ.In this post we're going to be looking at the distribution ...

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‘Student’, on Kurtosis

July 9, 2015
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‘Student’, on Kurtosis

W. S. Gosset (Student) provided this useful aid to help us remember the difference between platykurtic and leptokurtic distributions:('Student', 1927. Errors of routine analysis. Biometrika, 19, 151-164. See p. 160.)Here, β2 is the fourth standardized...

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Mathematical Statistics Lesson of the Day – An Example of An Ancillary Statistic

Mathematical Statistics Lesson of the Day – An Example of An Ancillary Statistic

Consider 2 random variables, and , from the normal distribution , where is unknown.  Then the statistic has the distribution . The distribution of does not depend on , so is an ancillary statistic for . Note that, if is unknown, then is not ancillary for .Filed under: Mathematical Statistics, Statistics, Statistics Lesson of the […]

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Mathematical Statistics Lesson of the Day – An Example of An Ancillary Statistic

Mathematical Statistics Lesson of the Day – An Example of An Ancillary Statistic

Consider 2 random variables, and , from the normal distribution , where is unknown.  Then the statistic has the distribution . The distribution of does not depend on , so is an ancillary statistic for . Note that, if is unknown, then is not ancillary for .Filed under: Mathematical Statistics, Statistics, Statistics Lesson of the […]

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