The DO Loop
Statistical programming in SAS with an emphasis on SAS/IML programs![The exponential of a matrix](https://blogs.sas.com/content/iml/files/2023/05/expmatrix3-640x336.png)
In SAS, you can approximate the exponential of a matrix by using the EXPMATRIX function in SAS IML software. This article discusses the exponential of a matrix: what it is, how to compute it, why it is useful, and why you should think of it as a linear map that
![Overlay a curve on a histogram in SAS](https://blogs.sas.com/content/iml/files/2023/04/HighlowHist4-640x336.png)
In a previous article, I showed how to overlay a density estimate on a histogram by using the Graph Template Language (GTL). However, a SAS programmer asked how to overlay a curve on a histogram when the curve is not a density estimate. In this case, the vertical axis for
![Compatible plot types in SAS](https://blogs.sas.com/content/iml/files/2013/07/truncnormal.png)
When the SAS statistical graphics (SG) procedures were designed in the early 2000s, a goal was to create a comprehensive Graph Template Language (GTL) and leverage the GTL by using SG procedures that perform common tasks easily without having to write any GTL. This project was hugely successful, and "ODS
![Venn diagrams that illustrate relationships between sets](https://blogs.sas.com/content/iml/files/2023/04/Venn2-640x336.png)
A previous article discusses how to compute the union, intersection, and other subsets of a pair of sets. In that article, I displayed a simple Venn diagram (reproduced to the right) that illustrates the intersection and difference between two sets. The diagram uses a red disk for one set, a
![The joy of sets](https://blogs.sas.com/content/iml/files/2023/04/sets4-640x336.png)
The fundamental operations on sets are union, intersection, and set difference, all of which are supported directly in the SAS IML language. While studying another programming language, I noticed that the language supports an additional operation, namely the symmetric difference between two sets. The language also supports query functions to
![Should you use the Wald confidence interval for a binomial proportion?](https://blogs.sas.com/content/iml/files/2023/04/WaldCI3-640x336.png)
The "Teacher’s Corner" of The American Statistician enables statisticians to discuss topics that are relevant to teaching and learning statistics. Sometimes, the articles have practical relevance, too. Andersson (2023) "The Wald Confidence Interval for a Binomial p as an Illuminating 'Bad' Example," is intended for professors and masters-level students in