278 search results for "Anova"

R User Group Activity for Q1 2014

March 27, 2014
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R User Group Activity for Q1 2014

by Joseph Rickert Worldwide R user group activity for the first Quarter of 2014 appears to be way up compared to previous years as the following plot shows. The plot was built by counting the meetings on Revolution Analytics R Community Calendar. R users continue to value the live, in person events and face-to-face meetings with their peers. Moreover,...

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Seasonal Unit Roots

March 26, 2014
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Seasonal Unit Roots

As discussed in the MAT8181 course, there are – at least – two kinds of non-stationary time series: those with a trend, and those with a unit-root (they will be called integrated). Unit root tests cannot be used to assess whether a time series is stationary, or not. They can only detect integrated time series. And the same holds...

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Normality and Testing for Normality

March 21, 2014
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Normality and Testing for Normality

How do we test for normality, and are normality tests really sensitive in the tails?

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Using R: barplot with ggplot2

March 19, 2014
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Using R: barplot with ggplot2

Ah, the barplot. Loved by some, hated by some, the first graph you’re likely to make in your favourite office spreadsheet software, but a rather tricky one to pull off in R. Or, that depends. If you just need a barplot that displays the value of each data point as a bar — which is

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MoneyPuck – Best subsets regression of NHL teams

March 17, 2014
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MoneyPuck – Best subsets regression of NHL teams

Spring is at hand and it is a time of renewal, March Madness and to settle scores in the NHL.  There are many scores to be settled: Flyers vs. Penguins, Blackhawks vs. Red Wings, Leafs vs. Habs and pretty much everyone else vs. the Bruins.  L...

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An R "meta" book

March 13, 2014
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by Joseph Rickert I am a book person. I collect books on all sorts of subjects that interest me and consequently I have a fairly extensive collection of R books, many of which I find to be of great value. Nevertheless, when I am asked to recommend an R book to someone new to R I am usually flummoxed....

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Generalized Linear Mixed Models in Ecology and in R

March 12, 2014
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Generalized Linear Mixed Models in Ecology and in R

I had a nice workshop two weeks ago in Tübingen (south-germany) concerning Generalized Linear Mixed Models (GLMM) in R. The course was given by two ecologist: Dr. Pius and Fränzi Korner-Nievergelt  that spend now half of their time doing statistical consulting (http://www.oikostat.ch/navigation_engl.htm). Nice reference concerning GLMMs are: the 2009 Bolker paper (paper),  the 2007 book

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Consecutive Numbers in Lottery Draws

March 2, 2014
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A historian, a data scientist, a programmer, a mathematician, and a philosopher discuss the question, how likely it is that a lottery draw (6 out of 49) contains two consecutive numbers. The historian The historian argues that from 1955 up to 2011, there were 5026 lottery draws in Germany, every Saturday, and from 2000 on, two draws every...

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“Statistical Models with R” Course – Milano, October 24-25, 2013

February 28, 2014
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“Statistical Models with R” Course – Milano, October 24-25, 2013

"Statistical Models with R" CourseMarch 27 and 28, 2014 Course description This two-day course shows a wide variety of statistical models with R ranging from Linear Models (LM) to Generalized Linear Models (GLM) modelling, in order to provide a broad … Continue reading →

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Example 2014.3: Allow different variances by group

February 27, 2014
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Example 2014.3: Allow different variances by group

One common violation of the assumptions needed for linear regression is heterscedasticity by group membership. Both SAS and R can easily accommodate this setting. Our data today comes from a real example of vitamin D supplementation of milk. Four sup...

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