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Analytics
Melissa Savage 0
Analytics helping transportation officials get the job done in tight financial times

The American Association of State Highway Transportation Officials recently released a top 10 list of transportation issues that will be “talked, written or tweeted and legislated about” in 2012.   As expected, funding constraints and Congressional action on reauthorization appear on the list but the group also notes that natural disaster

Advanced Analytics
Rick Wicklin 0
Use the Cholesky transformation to correlate and uncorrelate variables

A variance-covariance matrix expresses linear relationships between variables. Given the covariances between variables, did you know that you can write down an invertible linear transformation that "uncorrelates" the variables? Conversely, you can transform a set of uncorrelated variables into variables with given covariances. The transformation that works this magic is

Data Visualization
Sanjay Matange 0
Comparative density plots

Recently a user posted a question on the SAS/GRAPH and ODS Graphics Communities page on how to plot the normal density curves for two classification levels in the same graph. We have often seen examples of a  distribution plot of one variable using a histogram with normal and kernel density curves.  Here is a simple example: Code Snippet:

Data Visualization
Dan Heath 0
A (tool)tip for band plots

Recently, I had a discussion with a user concerning the volume of imagemap data generated for an interactive,  web-based visual contain a large number of graphs. The large amount of imagemap data was causing problems with the current version of their web browser. The graphs consisted of either bar charts

Data Visualization
Sanjay Matange 0
Nested graphs

Here are a couple of bar charts showing the city mileage of cars by Type and Origin using the SGPLOT procedure from the sashelp.cars dataset. title 'Vehicle Mileage by Type'; proc sgplot data=cars; format mpg_city 4.1; vbar type / response=mpg_city stat=mean datalabel; xaxis display=(nolabel); run; title 'Counts by Country'; proc sgplot

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