Monthly Archives: August 2011

Meta-analysis

August 7, 2011
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Meta-analysis

Introduction Effect estimation is an important task in modern research. An example is the identification of risk factors for disease and the qualification of medical treatments. Usually, researchers are interested in estimating the global, common effect. Since actual effects tend to differ across populations, estimates based on sample of a particular population seldomly generalize well.

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Usability

August 7, 2011
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Usability. I am not an expert in Human-Computer Interaction (HCI) at all. Worse, I make the crappiest looking interfaces, typically. So, that's said. Usability. Wikipedia writes that "sability is the ease of use and learnability of a ...

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R popularity – steady growth and New York Times

August 6, 2011
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R popularity – steady growth and New York Times

I have just came up with an idea how to test the wikipedia search traffic visualisation functions that I wrote about in my previous post. I decided to check if R is really gaining popularity that fast. ar <- wikiStat("R_(programming_language)", … Continue reading →

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Fitting mixture distributions with the R package mixtools

Fitting mixture distributions with the R package mixtools

My last two posts have been about mixture models, with examples to illustrate what they are and how they can be useful.  Further discussion and more examples can be found in Chapter 10 of Exploring Data in Engineering, the Sciences, and Medicine.  One important topic I haven’t covered is how to fit mixture models to datasets like the Old Faithful geyser...

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Visualising Wikipedia search statistics with R

August 6, 2011
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Visualising Wikipedia search statistics with R

I have been playing with R to parse html. After reading about visualising “fantasy football” search traffic with RGoogleTrends at The Log Cabin blog I decided to write a few functions to do similar things with Wikipedia search statistics. This … Continue reading →

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Programmers Should Know R

August 6, 2011
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Programmers Should Know R

Programmers should definitely know how to use R. I don’t mean they should switch from their current language to R, but they should think of R as a handy tool during development.Again and again I find myself working with Java code like the following. td.linenos { background-color: #f0f0f0; padding-right: 10px; } span.lineno { background-color: #f0f0f0; Related posts:

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Number of components in a mixture

August 5, 2011
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Number of components in a mixture

I got a paper (unavailable online) to referee about testing for the order (i.e. the number of components) of a normal mixture. Although this is an easily spelled problem, namely estimate k in I came to the conclusion that it is a kind of ill-posed problem. Without a clear definition of what a component is,

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Upcoming R training classes, live from the experts

August 5, 2011
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Revolution Analytics is hosting several hands-on R training classes over the next few months, with in-person instruction from two leading package authors and experts from the R community. Diethelm Würtz from ETH Zurich will give a two-day master class on Portfolio Selection and Optimization in Practice. Prof Würtz leads the Rmetrics project, and will provide in-depth instruction on using...

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R as a cure for ‘mindless statistics’?

August 5, 2011
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Several years ago Gerd Gigerenzer wrote: “Statistical rituals largely eliminate statistical thinking in the social sciences. Rituals are indispensable for identification with social groups, but they should be the subject rather than the procedure of science. Statistical rituals largely eliminate … Continue reading →

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Positive coefficient regression in R

August 5, 2011
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Positive coefficient regression in R

Ever have a regression model where the coefficients don't make sense? I've been trying to predict electricity and gas consumption from daily activity schedules but a simple linear regression kept saying that demands should go down the more an activity is performed. Fortunately I found the nnls package and show here how you can use it to...

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