The DO Loop
Statistical programming in SAS with an emphasis on SAS/IML programs![The normal mixture distribution in SAS](https://blogs.sas.com/content/iml/files/2019/04/normalmix1.png)
Did you know that SAS provides built-in support for working with probability distributions that are finite mixtures of normal distributions? This article shows examples of using the "NormalMix" distribution in SAS and describes a trick that enables you to easily work with distributions that have many components. As with all
![A CUSUM test for autregressive models](https://blogs.sas.com/content/iml/files/2019/04/autoreg3-702x336.png)
The CUSUM test has many incarnations. Different areas of statistics use different assumption and test for different hypotheses. This article presents a brief overview of CUSUM tests and gives an example of using the CUSUM test in PROC AUTOREG for autoregressive models in SAS. A CUSUM test uses the cumulative
![The CUSUM test for randomness of a binary sequence](https://blogs.sas.com/content/iml/files/2019/04/cusum1-640x336.png)
Many statistical tests use a CUSUM statistic as part of the test. It can be confusing when a researcher refers to "the CUSUM test" without providing details about exactly which CUSUM test is being used. This article describes a CUSUM test for the randomness of a binary sequence. You start
![Create your own version of Anscombe's quartet: Dissimilar data that have similar statistics](https://blogs.sas.com/content/iml/files/2019/04/Anscombe4.png)
I think every course in exploratory data analysis should begin by studying Anscombe's quartet. Anscombe's quartet is a set of four data sets (N=11) that have nearly identical descriptive statistics but different graphical properties. They are a great reminder of why you should graph your data. You can read about
![Efficient evaluation of a quadratic form](https://blogs.sas.com/content/iml/files/2019/04/quadform1-500x336.png)
A quadratic form is a second-degree polynomial that does not have any linear or constant terms. For multivariate polynomials, you can quickly evaluate a quadratic form by using the matrix expression x` A x This computation is straightforward in a matrix language such as SAS/IML. However, some computations in statistics
![4 ways to compute an SSCP matrix](https://blogs.sas.com/content/iml/files/2017/01/ProgrammingTips-2.png)
In numerical linear algebra, there are often multiple ways to solve a problem, and each way is useful in various contexts. In fact, one of the challenges in matrix computations is choosing from among different algorithms, which often vary in their use of memory, data access, and speed. This article