Posted on Categories Opinion, Statistics, TutorialsTags , ,

A while back Simon Jackson and Kara Woo shared some great ideas and graphs on grouped bar charts and density plots (link). Win-Vector LLC‘s Nina Zumel just added a graph of this type to the development version of WVPlots.

Nina has, as usual, some great documentation here.

Posted on Tags , , , 7 Comments on WVPlots: example plots in R using ggplot2

## WVPlots: example plots in R using ggplot2

Nina Zumel and I have been working on packaging our favorite graphing techniques in a more reusable way that emphasizes the analysis task at hand over the steps needed to produce a good visualization. The idea is: we sacrifice some of the flexibility and composability inherent to ggplot2 in R for a menu of prescribed presentation solutions (which we are sharing on Github).

For example the plot below showing both an observed discrete empirical distribution (as stems) and a matching theoretical distribution (as bars) is a built in “one liner.”

Please read on for some of the ideas and how to use this package. Continue reading WVPlots: example plots in R using ggplot2

Posted on Categories Expository Writing, Mathematics, Opinion, Statistics, Tutorials1 Comment on Automatic bias correction doesn’t fix omitted variable bias

## Automatic bias correction doesn’t fix omitted variable bias

Page 94 of Gelman, Carlin, Stern, Dunson, Vehtari, Rubin “Bayesian Data Analysis” 3rd Edition (which we will call BDA3) provides a great example of what happens when common broad frequentist bias criticisms are over-applied to predictions from ordinary linear regression: the predictions appear to fall apart. BDA3 goes on to exhibit what might be considered the kind of automatic/mechanical fix responding to such criticisms would entail (producing a bias corrected predictor), and rightly shows these adjusted predictions are far worse than the original ordinary linear regression predictions. BDA3 makes a number of interesting points and is worth studying closely. We work their example in a bit more detail for emphasis. Continue reading Automatic bias correction doesn’t fix omitted variable bias

Posted on Categories TutorialsTags , , , 13 Comments on How to remember point shape codes in R

## How to remember point shape codes in R

I suspect I am not unique in not being able to remember how to control the point shapes in R. Part of this is a documentation problem: no package ever seems to write the shapes down. All packages just use the “usual set” that derives from S-Plus and was carried through base-graphics, to grid, lattice and ggplot2. The quickest way out of this is to know how to generate an example plot of the shapes quickly. We show how to do this in ggplot2. This is trivial- but you get tired of not having it immediately available. Continue reading How to remember point shape codes in R