Tag: Statistical Programming

Programming Tips
Rick Wicklin 0
Distances on rectangular grids

Given a rectangular grid with unit spacing, what is the expected distance between two random vertices, where distance is measured in the L1 metric? (Here "random" means "uniformly at random.") I recently needed this answer for some small grids, such as the one to the right, which is a 7 x 6

Analytics
Rick Wicklin 0
Kernel regression in SAS

A SAS programmer recently asked me how to compute a kernel regression in SAS. He had read my blog posts "What is loess regression" and "Loess regression in SAS/IML" and was trying to implement a kernel regression in SAS/IML as part of a larger analysis. This article explains how to

Programming Tips
Rick Wicklin 0
Distance correlation

Correlation is a statistic that measures how closely two variables are related to each other. The most popular definition of correlation is the Pearson product-moment correlation, which is a measurement of the linear relationship between two variables. Many textbooks stress the linear nature of the Pearson correlation and emphasize that

Analytics | Learn SAS
Rick Wicklin 0
Principal component regression in SAS

A common question on discussion forums is how to compute a principal component regression in SAS. One reason people give for wanting to run a principal component regression is that the explanatory variables in the model are highly correlated which each other, a condition known as multicollinearity. Although principal component

Data Visualization | Learn SAS
Rick Wicklin 0
The path of zip codes

Toe bone connected to the foot bone, Foot bone connected to the leg bone, Leg bone connected to the knee bone,...              — American Spiritual, "Dem Bones" Last week I read an interesting article on Robert Kosara's data visualization blog. Kosara connected the geographic centers of the US zip codes in

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