June 2012

Workshop on Structural Equation Models

June 26, 2012 | Murtaza Haider

The Ted Rogers School of Management at Ryerson University is offering a one-day, hands–on workshop on Structural Equation Modelling. The workshop focuses on SEM theory and applications using R and Amos. Instructors: Professor Richard Michon and Christine Buske When: July 11, 2012 (8:30 to 3:30 pm) Where: TRS 3-099 (55 Dundas Street West, 9th ... [Read more...]

Grouped means (again)

June 26, 2012 | aghaynes

So, the post I did yesterday on aggregate seemed to go down well. One of the comments suggested I add an example. Other comments had other useful hints which I thought I’d pass on more formally. So here goes… The mtcars dataset in base has data on various aspects ... [Read more...]

How to Convert Rugby into Football/Soccer Scores

June 26, 2012 | diffuseprior

Following the Irish rugby team’s humiliating 60-0 defeat to New Zealand, an interesting question was posed on Twitter: what does a 60-0 result convert to in football/soccer? Intrigued, I decided to gather some data from both the English premier league (this season, more data collected and future blog ... [Read more...]

Shading regions of the normal: The Stanine scale

June 26, 2012 | FelixS

For the presentation of norm values, often stanines are used (standard nine). These values mark a person’s relativ position in comparison to the sample or to norm values. According to Wikipedia: The underlying basis for obtaining stanines is that a normal distribution is divided into nine intervals, each of ... [Read more...]

Bayesian Nonparametrics in R

June 25, 2012 | John Myles White

On July 25th, I’ll be presenting at the Seattle R Meetup about implementing Bayesian nonparametrics in R. If you’re not sure what Bayesian nonparametric methods are, they’re a family of methods that allow you to fit traditional statistical models, such as mixture models or latent factor models, ... [Read more...]

Strategy Diversification in R – follow up

June 25, 2012 | rbresearch

The strategies used in Strategy Diversification in R were labeled as Strategy1 and Strategy2. Strategy1 Indicator: 52 week Simple Moving Average Entry Rule: Buy 1000 shares when price crosses and closes above 52 week Simple Moving Average Exit Rule: Exit all positions when prices crosses and closes below 52 week Simple Moving Average Classification: ... [Read more...]

Rcpp 0.9.12

June 25, 2012 | Thinking inside the box

A bug-fix release 0.9.12 of Rcpp arrived earlier today on CRAN and is now in Debian too. This fixes a minor snafu with the Rcpp::Enviroment constructor following a minor change made for 0.9.11. It also reduces the number of unit tests running by de... [Read more...]

New R User Groups in Ankara, Toronto

June 25, 2012 | David Smith

Two new local R user groups to report this week. In Turkey, the Ankara R Users Group has just started up. No meetings are scheduled yet, so be sure to suggest a meeting time/location when you sign up. The Toronto-based R Matlab Users group focuses on financial services applications. ... [Read more...]

Olive Oil NIR/VIS Spectra – 001 (ChemSpec)

June 25, 2012 | jrcuesta

I continue with the practicing with ChemSpec, and this time I import seven spectra of olive oil. This time I have been more careful and I have the frequency column as numeric form the CSV file. Once I have the spectra (with and offset):Take in account ...
[Read more...]

Grouped means (or anything else…)

June 25, 2012 | aghaynes

An easy one today, but something that stumped me for a while* the first time I tried it out. How do you get a group mean (or other summary statistic) from R? Lets say you have a Y variable that represents repetitions for each of however many factors. You could ... [Read more...]

Example 9.36: Levene’s test for equal variances

June 25, 2012 | Ken Kleinman

The assumption of equal variances among the groups in analysis of variance is an expression of the assumption of homoscedasticity for linear models more generally. For ANOVA, this assumption can be tested via Levene's test. The test is a function of the residuals and means within each group, though various ...
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How many ecologists were on ECOLOG in 1992?

June 25, 2012 | Ted Hart

Remember 1992? I had just turned 13 and was still a year away from highschool when my true descent into nerdom and the internet would begin. Back then it was with a local BBS (Bulletin Board System) run by a guy in a trailer park named Charlie and a 1200 baud modem on ... [Read more...]

Making Reproducible Research Enjoyable

June 25, 2012 | Yihui Xie

Note: this is a contributed article for the ICSA Bulletin and the basic idea can be summarized in this picture. It is hard to convince people to think about reproducible research (RR). There are two parts of difficulties: (1) tools used to be for ex... [Read more...]

Grid2Polygons

June 25, 2012 | Jason C Fisher

I’d like to introduce you to the Grid2Polygons function; an R function for converting sp spatial objects from class SpatialGridDataFrame to SpatialPolygonsDataFrame. The significance of this conversion is that spatial polygons can be transformed to a different projection or datum with the spTransform function in package rgdal. Postscript ... [Read more...]

Hodgkin-Huxley model in R

June 24, 2012 | Markus Gesmann

One of the great research papers of the 20th century celebrates its 60th anniversary in a few weeks time: A quantitative description of membrane current and its application to conduction and excitation in nerve by Alan Hodgkin and Andrew Huxley. Only a...
[Read more...]

Split-plot 1: How does a linear mixed model look like?

June 24, 2012 | Luis

I like statistics and I struggle with statistics. Often times I get frustrated when I don’t understand and I really struggled to make sense of Krushke’s Bayesian analysis of a split-plot, particularly because ‘it didn’t look like’ a split-plot to … Continue reading → [Read more...]

useR 2012: main conference braindump

June 24, 2012 | civilstat

I knew R was versatile, but DANG, people do a lot with it: __ __ … I don’t think anyone actually believes that R is designed to make *everyone* happy. For me, R does about 99% of the things I … Continue reading → [Read more...]
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