Blog Archives

Repeated measures ANOVA with R (tutorials)

April 13, 2010
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Repeated measures ANOVA is a common task for the data analyst. There are (at least) two ways of performing “repeated measures ANOVA” using R but none is really trivial, and each way has it’s own complication/pitfalls (explanation/solution to which I was usually able to find through searching in the R-help mailing list). So for future reference, I am starting this page...

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Jeroen Ooms’s ggplot2 web interface – a new version released (V0.2)

April 12, 2010
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Good news. Jeroen Ooms released a new version of his (amazing) online ggplot2 web interface: yeroon.net/ggplot2 is a web interface for Hadley Wickham’s R package ggplot2. It is used as a tool for rapid prototyping, exploratory graphical analysis and education of statistics and R. The interface is written completely in javascript, therefore there is no need to install anything on the...

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Correlation scatter-plot matrix for ordered-categorical data

April 7, 2010
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Correlation scatter-plot matrix for ordered-categorical data

When analyzing a questionnaire, one often wants to view the correlation between two or more Likert questionnaire item’s (for example: two ordered categorical vectors ranging from 1 to 5). When dealing with several such Likert variable’s, a clear presentation of all the pairwise relation’s between our variable can be achieved by inspecting the (Spearman) correlation matrix (easily achieved in R...

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R-Node: a web front-end to R with Protovis

April 3, 2010
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R-Node: a web front-end to R with Protovis

Update (April 6 – 2010) : R-Node now has it’s own a website, with a dedicated google group (you can join it here) * * * * The integration of R into online web services is (for me) one of the more exciting prospects in R’s future. That is way I was very excited coming across Jamie...

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Quantile LOESS – Combining a moving quantile window with LOESS (R function)

April 1, 2010
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Quantile LOESS – Combining a moving quantile window with LOESS (R function)

In this post I will provide R code that implement’s the combination of repeated running quantile with the LOESS smoother to create a type of “quantile LOESS” (e.g: “Local Quantile Regression”). This method is useful when the need arise to fit robust and resistant (Need to be verified) a smoothed line for a quantile (an example for such a...

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The “Future of Open Source” Survey – an R user’s thoughts and conclusions

March 23, 2010
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The “Future of Open Source” Survey – an R user’s thoughts and conclusions

Over a month ago, David Smith published a call for people to participate in the “Future of Open Source” Survey. 550 people (and me) took the survey, and today I got an e-mail with the news that the 2010 survey results are analysed and where published in the “Future.Of.Open.Source blog” In the following (38 slides) presentation: I would like...

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Google spreadsheets + google forms + R = Easily collecting and importing data for analysis

March 13, 2010
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Someone on the R mailing list (link) asked: how can you easily (daily) collect data from many people into a spreadsheet and then analyse it using R. The answer people gave to it where on various ways of using excel.  But excel files (at least for now),  are not “on the cloud”.  A better answer might be to create a...

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A nice link: “Some hints for the R beginner”

March 7, 2010
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Patrick Burns just posted to the mailing list the following massage: There is now a document called “Some hints for the R beginner” whose purpose is to get people up and running with R as quickly as possible. Direct access to it is: http://www.burns-stat.com/pages/Tutor/hints_R_begin.html JRR Tolkien wrote a story (sans hobbits) called ‘Leaf by Niggle’ that has always resonated with me. I...

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Nutritional supplements efficacy score – Graphing plots of current studies results (using R)

February 25, 2010
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Nutritional supplements efficacy score – Graphing plots of current studies results (using R)

In this post I showcase a nice bar-plot and a balloon-plot listing recommended Nutritional supplements , according to how much evidence exists for thier benefits, scroll down to see it(and click here for the data behind it) * * * * The gorgeous blog “Information Is Beautiful” recently publish an eye candy post showing a “balloon race” image...

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Siegel-Tukey: a Non-parametric test for equality in variability (R code)

February 22, 2010
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Daniel Malter just shared on the R mailing list (link to the thread) his code for performing the Siegel-Tukey (Nonparametric) test for equality in variability. Excited about the find, I contacted Daniel asking if I could republish his code here, and he kindly replied “yes”. From here on I copy his note at full. p.s: (The R function can be downloaded from...

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