Monthly Archives: July 2009

Simple visualization of a 11X5 table (for WordPress 2.9 Features Vote Results)

July 31, 2009
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Simple visualization of a 11X5 table (for WordPress 2.9 Features Vote Results)

I guess this is not the number one post I would like to start with on this blog, but I feel the time is right for it (community-wise). I’ll move on to the subject matter in a moment, but first a short intro: This blog is written by Tal Galili. I am ...

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Kruskal-Wallis one-way analysis of variance

July 31, 2009
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If you have to perform the comparison between multiple groups, but you can not run a ANOVA for multiple comparisons because the groups do not follow a normal distribution, you can use the Kruskal-Wallis test, which can be applied when you can not make ...

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Analysis of variance: ANOVA, for multiple comparisons

July 30, 2009
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Analysis of variance: ANOVA, for multiple comparisonsThe ANOVA model can be used to compare the mean of several groups with each other, using a parametric method (assuming that the groups follow a Gaussian distribution).Proceed with the following example:The manager of a supermarket chain wants to see if the consumption in kilowatts of 4 stores between them are equal. He...

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Comparison of two proportions: parametric (Z-test) and non-parametric (chi-squared) methods

July 29, 2009
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Consider for example the following problem.The owner of a betting company wants to verify whether a customer is cheating or not. To do this want to compare the number of successes of one player with the number of successes of one of his employees, of w...

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Wilcoxon signed rank test

July 29, 2009
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Non-parametric statistical hypothesis test, for the comparison of the means between 2 paired samplesThe mayor of a city wants to see if pollution levels are reduced by closing the streets to the car traffic. This is measured by the rate of pollution every 60 minutes (8am 22pm: total of 15 measurements) in a day when traffic is open, and...

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Beta Verson of tikzDevice Released!

July 28, 2009
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The tikzDevice package provides a new graphics device for R which enables direct output of graphics in a LaTeX-friendly way. The device output consists of files containing instructions for the TikZ graphics language and may be imported directly into LaTeX documents using the \input{} command. The beta version of tikzDevice is now available here. An

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I know it’s been so long…

July 28, 2009
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Hey,I know it's been so long since last time I posted something in here, but I was really busy with my thesis and some other stuff, but now that I have more time I promise I'll post some interesting stuff in here, by the way, I found such an Interestin...

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Corpus Linguistics with R, Day 2

July 28, 2009
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R Lesson 2 text gsub ("second", "third", text) SEARCH-REPLACE-SUBJECT "This is a first example sentence." "And this is a third example sentence." > gsub ("n", "X", text) "This is a first example seXteXce." "AXd this is a secoXd example seXteXce." > gsub ("is", "was", text) "Thwas was a first example

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Corpus Linguistics with R, Day 1

July 28, 2009
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(This post documents the first day of a class on R that I took at ESU C&T. I is posted here purely for my own use.) R Lesson 1 > 2+3; 2/3; 2^3 5 0.6666667 8 --- Fundamentals - Functions > log(x=1000, base=10) 3 --- (Formals describes the syntax of other

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Wilcoxon-Mann-Whitney rank sum test (or test U)

July 27, 2009
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Comparison of the averages of two independent groups of samples, of which we can not assume a distribution of Gaussian type; is also known as Mann-Whitney U-test.You want to see if the mean of goals suffered by two football teams over the years is the same. Are below the number of goals suffered by each team in 6 games...

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