Are halo effects real or illusory?  Much has been written arguing that rating scales contain extensive amounts of measurement bias.  Some tells us to avoid ratings altogether (What do customers really want?).  Others warn against the use of ratings scales without major adjustments (e.g., overcoming scale usage heterogeneity with ... [Read more...]

Last week, Alyssa got the boot and Jinkx kept her place. And I totally called it with my first model that accounted for the proportional hazards assumption. I think the model is having a little more success as the season plods on. Before I get to the predictions for episode 10, ... [Read more...]

With spring in the air, I thought it would be fun to do a series on (spring) cleaning data. The posts will follow my efforts to to download the data, import into R, cleaned it up, merge the different files, add columns of information created, and then ... [Read more...]

Last week I ran an introductory workshop on the analysi [...] [Read more...]

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Quick reminder: The next Cologne R user group meeting is scheduled for this Friday, 12 April 2013. We will discuss cluster analysis and shiny. Further details and the agenda are available on our KölnRUG Meetup site. Please sign up if you would like to come along. Notes from the last Cologne ... [Read more...]

think of the pesquisa nacional por amostra de domicilios (pnad) as the brazilian census for off-years - the ones that don't end in zero.  the principal household survey for the nation of brazil, pnad measures general education, labor, income, and ... [Read more...]

The Dirichlet process provides a very interesting approach to understand group assignments and models for clustering effects.   Often time we encounter the k-means approach.  However, it is necessary to have a fixed number of clusters.  Often we encounter situations where we don’t know how many fixed clusters we need.  ... [Read more...]

A very special package that I am rather excited about arrived in the mail recently. The package contained a set of 6-sided dice. These dice, however, don’t have the standard numbers one to six on their faces. Instead, they have assorted numbers between zero and nine. Here’s the ... [Read more...]

Last month I attended the CeBIT trade fair in Hannover. Besides the so called “shareconomy” there was also another main topic across all expedition halls - Big Data. This subject is not completely new and I think that a lot of you also have experiences with some of the tools ... [Read more...]

R has many ways to store information.  Most of the time, our data comes in the form of a dataset, which we bring into R as a data.frame object. However, there are times when we want to use matrices as well. This post will show you how matrices can... [Read more...]

I am listening to the audiobook Sync: How Order Emerges from Chaos in the Universe, Nature, and Daily Lifeby Steven Strogatz which I got from Audible. Obviously a mathematical book is not ideal to listen to, but lacking illustrations I can ma... [Read more...]

I'm always worried about CRAN: a system maintained by FTP and emails from real humans (basically one of Uwe, Kurt or Prof Ripley). I'm worried for two reasons: the number of R packages is growing exponentially; time and time again I see frustrations ... [Read more...]

Native GUI client access to MS-SQL and MySQL We can use Oracle SQL Developer with the jTDS driver to access Microsoft SQL Server. Note: jTDS version 1.3.0 did not work for me; I had to use version 1.2.6. Detailed instructions can be found here. We can use MySQL Workbench to access MySQL ... [Read more...]

This post comes with some big health warnings. The recent events in Leeds highlight the difficulties faced in judging the results of surgery by individual hospital. A clear requirement is timely access to data in a form easily digestible by the public. Here I’ve scraped the publically available data ... [Read more...]

Today, I want to share the Retirement : simulating wealth with random returns, inflation and withdrawals – Shiny web application (code at GitHub). This application was developed and contributed by Pierre Chretien, I only made minor updates. This is application is a great example of how easy it is to convert your ... [Read more...]

I’m gonna share a short code snippet that I thought was interesting. This post is inspired by one of my engineering computation classes at Rice. The program initializes a pair of coordinates ‘z’ and iteratively updates z by matrix multiplication based on some random number generation criteria. After each ... [Read more...]

In data science work you often run into cryptic sentences like the following: Age adjusted death rates per 10,000 person years across incremental thirds of muscular strength were 38.9, 25.9, and 26.6 for all causes; 12.1, 7.6, and 6.6 for cardiovascular disease; and 6.1, 4.9, and 4.2 for cancer (all P __ 0.01 for linear [...] Related posts:Level fit summaries can be ... [Read more...]

PCA is widely used method for finding patterns in high-dimensional data. Whether you use it to compress large matrix or to remove one of the principal components in biological datasets, you’ll end up with the task of performing series of … Continue reading → [Read more...]

Use R to specify factors, recode variables and begin by-group analyses. Video Files This file contains data on pain score after laparoscopic vs. open hernia repair. Age, gender and primary/recurrent hernia also included. The ultimate aim here is to work out which of these factors are associated with more ... [Read more...]