271 search results for "anova"

Simpson’s Paradox Is Back

April 21, 2014
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Simpson’s Paradox Is Back

The latest issue of the American Statistician has a set of thought-provoking point/counterpoint papers on Simpson’s Paradox, with a tie-in to the controversial issue of causality. (I will not address the causality issue here.) Since I have long had my own thoughts about Simpson’s, I’ll postpone the topic I had planned to post this week,

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Interpreting interaction coefficient in R (Part1 lm)

April 8, 2014
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Interpreting interaction coefficient in R (Part1 lm)

Interaction are the funny interesting part of ecology, the most fun during data analysis is when you try to understand and to derive explanations from the estimated coefficients of your model. However you do need to know what is behind these estimate, there is a mathematical foundation between them that you need to be aware

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Scraping organism metadata for Treebase repositories from GOLD using Python and R

Scraping organism metadata for Treebase repositories from GOLD using Python and R I recently wanted to get hold of habitat/phenotype/sequencing metadata for the individual organisms of an archived Treebase project.) The GOLD database holds more than 18000 full genomes. For many of these it provides pretty good metadata (GOLDcards) which are indirectly linked to...

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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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