Articles by gerhi

Running R on 32 cores for 2USD/h

May 14, 2014 | gerhi

Even though most modern computers already have four cores that can be used to speed up analysis – see here for a description. However, after starting to do more simulation studies it became apparent that this is highly impractical. The solution: Running R via R-studio on Amazons cloud servers. Thanks to ... [Read more...]

All you need is text – Markdown (via pandoc) for academia

May 1, 2013 | gerhi

Many students struggle to find an adequte format for their thesis. Ironically the advent of “modern” WYSIWYG programms seems to make it harder to consistently format a text. While learning LaTeX may be a bit too much to ask for, markdown is a very minimal language that together with pandoc ... [Read more...]

Evolution of a logistic regression

January 28, 2013 | gerhi

In my last post I showed how one can easily summarize the outcome of a logistic regression. Here I want to show how this really depends on the data-points that are used to estimate the model. Taking a cue from the evolution of a correlation I have plotted the estimated ... [Read more...]

Visualizing GIS data with R and Open Street Map

October 8, 2011 | gerhi

In this post I way to share with you some code to use Openstreetmap – maps as a backdrop for a data visualization. We will use the RgoogleMaps-package for R. In the following I will show you how to make this graph. 1. Download the map I wanted to take a closer ... [Read more...]

Simulation studies in R – Using all cores and other tips

September 16, 2011 | gerhi

After working more seriously with simulations I noticed some updates were necessary to my previous setup. Most notably are the following three: It is very handy to explicitly call the different scenarios instead of using nested loops Storing intermediate results in single files obliviates the need to rerun an almost ... [Read more...]

Dump MySQL to CSV using R

August 10, 2011 | gerhi

Based on a related post on one of my favorite python-lists I remembered, that I wrote a similar snipplet some time ago. So if you want to dump your whole MySQL database to csv-files you can recycle the following code: ?Download mysql2cvs.R1 2 3 4 5 6 7 8 9 require(RMySQL) m [Read more...]

GIS on a shoestring – Getting traveltimes from google

July 2, 2011 | gerhi

The analysis of geospatial information is currently a big trend in medicine and public health. Even though some may want to convince you that this can only be achieved with the latest and most expensive software, I am not convinced. First, analysis  of spatial data dates back to at least 1856 ... [Read more...]

RStudio the missing link between your brain and statistics

May 18, 2011 | gerhi

RStudio is a graphical user interface for R. Or as the developers put it. RStudio™ is a new integrated development environment (IDE) for R. RStudio combines an intuitive user interface with powerful coding tools to help you get the most out of R.   While there have been a few projects (... [Read more...]

Illustrating CFAs – Graphviz

December 9, 2010 | gerhi

So after yesterdays post you probably ran this fancy new confirmatory factor analysis (CFA) – showed your friends all the cool fit stats and… nothing. As important as doing things right is being able to let others know that. For CFA the method of choice to illustrate the connections between variables ... [Read more...]

All together now – Confirmatory Factor Analysis in R

December 8, 2010 | gerhi

Describing multivariate data is not easy. Especially, if you think that statisticians have not developed any new tools after the ANOVA and principal component analysis (PCA). For social and experimental scientists the most important new technique are structural equation models that combine measurement models (that substitute reliability analysis and PCA) ... [Read more...]

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