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Rick WicklinFebruary 27, 2023 0

In applied mathematics, there is a large collection of "special functions." These function appera in certain applications, often as the solution to a differential equation, but also in the definition of probability distributions. For example, I have written about Bessel functions, the complete and incomplete gamma function, and the complete

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Analytics | Learn SAS | Programming Tips

Rick WicklinFebruary 20, 2023 2

Simulate from a bounded distribution that has a specified mean

A SAS programmer asked for help to simulate data from a distribution that has certain properties. The distribution must be supported on the interval [a, b] and have a specified mean, μ, where a < μ < b. It turns out that there are infinitely many distributions that satisfy these

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Analytics | Programming Tips

Rick WicklinFebruary 13, 2023 0

Estimate the pth root of a Markov transition matrix

You can use a Markov transition matrix to model the transition of an entity between a set of discrete states. A transition matrix is also called a stochastic matrix. A previous article describes how to use transition matrices for stochastic modeling. You can estimate a Markov transition matrix by using

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Data Visualization | Learn SAS | Programming Tips

Rick WicklinFebruary 8, 2023 5

A random walk inside a heart

SAS programmers love to make special graphs for Valentine's Day. In fact, there is a long history of heart-shaped graphs and love-inspired programs written in SAS! Last year, I added to the collection by showing how a ball bounces on a heart-shaped billiards table. This year, I create a similar

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Learn SAS | Programming Tips

Rick WicklinFebruary 6, 2023 3

How to use Git to share SAS programs

This article is about how to use Git to share SAS programs, specifically how to share libraries of SAS IML functions. Some IML programmers might remember an earlier way to share libraries of functions: SAS/IML released "packages" in SAS 9.4m3 (2015), which enable you to create, document, share, and use

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Data Visualization | Learn SAS | Programming Tips

Rick WicklinFebruary 1, 2023 0

Colorblind-safe palettes in SAS

SAS supports the ColorBrewer system of color palettes from the ColorBrewer website (Brewer and Harrower, 2002). The ColorBrewer color ramps are available in SAS by using the PALETTE function in SAS IML software. The PALETTE function supports all ColorBrewer palettes, but some palettes are not interpretable by people with color

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Data Visualization | Learn SAS | Programming Tips

Rick WicklinJanuary 30, 2023 1

Tips for making colorblind-safe statistical graphs

Did you know that about 8% of the world's men are colorblind? (More correctly, 8% of men are "color vision deficient," since they see colors, but not all colors.) Because of the "birthday paradox," in a room that contains eight men, the probability is 50% that at least one is

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Learn SAS | Programming Tips

Rick WicklinJanuary 25, 2023 0

Write to the log from SAS IML programs

I previously discussed how to use the PUTLOG statement to write a message from the DATA step to the log in SAS. The PUTLOG statement is commonly used to write notes, warnings, and errors to the log. This article shows how to use the PRINTTOLOG subroutine in SAS IML software

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Learn SAS | Programming Tips

Rick WicklinJanuary 23, 2023 1

Use the PUTLOG statement to write errors, warning, and notes to the SAS log

Many experienced SAS programmers use the PUT statement to write messages to the log from a DATA step. But did you know that SAS supports the PUTLOG function, which is another way to write a message to the log? I use the PUTLOG statement in the DATA step for the

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Analytics | Programming Tips

Rick WicklinJanuary 16, 2023 1

Simulate data from a logistic regression model: How the intercept parameter affects the probability of the event

This article shows that you can use the intercept parameter to control the probability of the event in a simulation study that involves a binary logistic regression model. For simplicity, I will simulate data from a logistic regression model that involves only one explanatory variable, but the main idea applies

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