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Learn SAS | Programming Tips

Rick WicklinDecember 12, 2022 0

Properties of the Hadamard product

I always emphasize efficiency in statistical programming. I have previously written about why you should never multiply with a large diagonal matrix in the SAS IML language. The reason is that it is more efficient to use elementwise multiplication than matrix multiplication. Specifically, if d is a column vector, then

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Data Visualization | Learn SAS | Programming Tips

Rick WicklinDecember 7, 2022 0

Art in SAS: Christmas wrapping paper

For Christmas 2021, I wrote an article about palettes of Christmas colors, chiefly shades of red, green, silver, and gold. One of my readers joked that she would like to use my custom palette to design her own Christmas wrapping paper! I remembered her jest when I saw some artwork

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Learn SAS | Programming Tips

Rick WicklinNovember 30, 2022 0

Ladders: A probabilistic card trick

A probabilistic card trick is a trick that succeeds with high probability and does not require any skill from the person performing the trick. I have seen a certain trick mentioned several times on social media. I call it "ladders" or the "ladders game" because it reminds me of the

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Advanced Analytics | Analytics | Artificial Intelligence | Learn SAS | Students & Educators

Jos van DongenNovember 28, 2022 0

SAS Energy Game: Serious gaming maakt leren leuk

Inzicht krijgen in de kracht van analytics én leren omgaan met analytische software. En dat terwijl je gewoon een spel speelt. Dat is de SAS Energy Game. Inmiddels hebben al honderden studenten het spel gespeeld en daarmee hun analytische vaardigheden versterkt. Meer mensen kennis laten maken met analytics Data is

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Energy & Utilities

Learn SAS | Programming Tips

Rick WicklinNovember 28, 2022 0

Simulate poker hands in SAS

A SAS programmer was trying to simulate poker hands. He was having difficulty because the sampling scheme for simulating card games requires that you sample without replacement for each hand. In statistics, this is called "simple random sampling." If done properly, it is straightforward to simulate poker hands in SAS.

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Data Visualization | Learn SAS | Programming Tips

Rick WicklinNovember 14, 2022 0

Profile plots in SAS

A profile plot is a compact way to visualize many variables for a set of subjects. It enables you to investigate which subjects are similar to or different from other subjects. Visually, a profile plot can take many forms. This article shows several profile plots: a line plot of the

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Analytics | Data Visualization | Learn SAS | Programming Tips

Rick WicklinNovember 7, 2022 0

The area of the convex hull of random points

I recently blogged about how to compute the area of the convex hull of a set of planar points. This article discusses the expected value of the area of the convex hull for n random uniform points in the unit square. The article introduces an exact formula (due to Buchta,

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Analytics | Learn SAS | Programming Tips

Rick WicklinNovember 2, 2022 0

The area and perimeter of a convex hull

The area of a convex hull enables you to estimate the area of a compact region from a set of discrete observations. For example, a biologist might have multiple sightings of a wolf pack and want to use the convex hull to estimate the area of the wolves' territory. A

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Learn SAS | Programming Tips

Rick WicklinOctober 31, 2022 0

A trick to combine and split strings

Every year, I write a special article for Halloween in which I show a SAS programming TRICK that is a real TREAT! This year, the trick is to concatenate two strings into a single string in a way that guarantees you can always recover the original strings. I learned this

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Analytics | Data Visualization | Learn SAS

Rick WicklinOctober 26, 2022 0

Visualize dependencies of missing values

A SAS programmer asked how to create a graph that shows whether missing values in one variable are associated with certain values of another variable. For example, a patient who is supposed to monitor his blood glucose daily might have more missing measurements near holidays and in the summer months

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Analytics | Learn SAS | Programming Tips

Rick WicklinOctober 24, 2022 0

Implement binary logistic regression from first principles

I recently gave a presentation about the SAS/IML matrix language in which I emphasized that a matrix language enables you to write complex analyses by using only a few lines of code. In the presentation, I used least squares regression as an example. One participant asked how many additional lines

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Analytics | Learn SAS | Programming Tips

Rick WicklinOctober 19, 2022 0

On solving rank-deficient systems of equations in SAS

Recently, I needed to write a program that can provide a solution to a regression-type problem, even when the data are degenerate. Mathematically, the problem is an overdetermined linear system of equations X*b = y, where X is an n x p design matrix and y is an n x 1 vector. For most

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Learn SAS | Programming Tips

Leonid BatkhanOctober 18, 2022 0

Adaptive SAS programming for the Software Development Life Cycle

Leonid Batkhan reveals programming technique to build adaptive SAS programs to facilitate transition between various environments for a smoother SDLC.

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Analytics | Learn SAS

Rick WicklinOctober 12, 2022 0

Reduced regression models and tests for linear hypotheses

On a SAS discussion forum, a statistical programmer asked about how to understand the statistics that are displayed when you use the TEST statement in PROC REG (or other SAS regression procedures) to test for linear relationships between regression coefficients. The documentation for the TEST statement in PROC REG explains

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Learn SAS | Programming Tips

Rick WicklinOctober 10, 2022 0

The expected volume of a random tetrahedron in a cube

One of the benefits of social media is the opportunity to learn new things. Recently, I saw a post on Twitter that intrigued me. The tweet said that the expected volume of a random tetrahedron in the unit cube (in 3-D) is E[Volume] = 0.0138427757.... This number seems surprisingly small!

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Learn SAS | Programming Tips

Rick WicklinOctober 5, 2022 0

Checksums and data integrity in SAS programs

Have you ever typed your credit card into an online order form and been told that you entered the wrong number? Perhaps you wondered, "How do they know that the numbers I typed do not make a valid credit card number?" The answer is that credit card numbers and other

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Analytics | Learn SAS | Programming Tips

Rick WicklinOctober 3, 2022 0

Compute moments of probability distributions in SAS

A previous article discusses the definitions of three kinds of moments for a continuous probability distribution: raw moments, central moments, and standardized moments. These are defined in terms of integrals over the support of the distribution. Moments are connected to the familiar shape features of a distribution: the mean, variance,

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Learn SAS | Programming Tips

Rick WicklinSeptember 26, 2022 0

Display correlations in a list format

The correlations between p variables are usually displayed by using a symmetric p x p matrix of correlations. However, sometimes you might prefer to see the correlations listed in "long form" as a three-column table, as shown to the right. In this table, each row shows a pair of variables and the

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Analytics | Learn SAS

Rick WicklinSeptember 21, 2022 0

The noncentral t distribution in SAS

The noncentral t distribution is a probability distribution that is used in power analysis and hypothesis testing. The distribution generalizes the Student t distribution by adding a noncentrality parameter, δ. When δ=0, the noncentral t distribution is the usual (central) t distribution, which is a symmetric distribution. When δ >

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Advanced Analytics | Data Management | Data Visualization | Learn SAS | Machine Learning

Suzanne MorgenSeptember 20, 2022 0

3 data scientist jobs and how to land them

The question to ask is no longer, “Do you want to be a data scientist?” But rather, “What kind of data scientist do you want to be?”

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Learn SAS | Programming Tips

Rick WicklinSeptember 19, 2022 0

Generate random ID values for subjects in SAS

A common question on SAS discussion forums is how to use SAS to generate random ID values. The use case is to generate a set of random strings to assign to patients in a clinical study. If you assign each patient a unique ID and delete the patients' names, you

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Analytics | Learn SAS | SAS Events

Diana MarisSeptember 14, 2022 0

Intelligent Decisioning: Ensuring fairness in analytically-driven decision making

Attend this session during the SAS Explore event on Sept 27-29 or view the recording at your convenience. We will showcase the use of SAS Intelligent Decisioning, SAS Model Manager, and SAS Visual Analytics on the SAS Viya platform for a solution that helps mitigate inequitable credit decisions.

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Learn SAS | Programming Tips

Rick WicklinSeptember 14, 2022 0

Base 26: A mapping from integers to strings

I recently showed how to represent positive integers in any base and gave examples of base 2 (binary), base 8 (octal), and base 16 (hexadecimal). One fun application is that you can use base 26 to associate a positive integer to every string of English characters. This article shows how

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Learn SAS | Students & Educators

Adriana RojasSeptember 13, 2022 0

“Yo quería ser una de las personas que consiguiesen dar sentido a estos grandes datos”

El perfil de un analista de datos es cada vez más demandado en el plano profesional. Ante este panorama, el equipo de Academics de SAS y la Universidad Francisco de Vitoria (UFV) unieron fuerzas en el año 2020 para impulsar el Grado en Business Analytics powered by SAS con la

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English | SAS Spain

Learn SAS | Programming Tips

Rick WicklinSeptember 12, 2022 0

Convert integers from base 10 to another base

An integer can be represented in many ways. This article shows how to represent a positive integer in any base b. The most common base is b=10, but other popular bases are b=2 (binary numbers), b=8 (octal), and b=16 (hexadecimal). Each base represents integers in different ways. Think of a

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Analytics | Learn SAS | Programming Tips

Rick WicklinSeptember 7, 2022 0

A test for monotonic sequences and functions

Monotonic transformations occur frequently in math and statistics. Analysts use monotonic transformations to transform variable values, with Tukey's ladder of transformations and the Box-Cox transformations being familiar examples. Monotonic distributions figure prominently in probability theory because the cumulative distribution is a monotonic increasing function. For a continuous distribution that is

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Learn SAS | Programming Tips

Rick WicklinAugust 31, 2022 0

Two types of syntax for the SELECT-WHEN statement in SAS

The SELECT-WHEN statement in the SAS DATA step is an alternative to using a long sequence of IF-THEN/ELSE statements. Although logically equivalent to IF-THEN/ELSE statements, the SELECT-WHEN statement can be easier to read. This article discusses the two distinct ways to specify the SELECT-WHEN statement. You can use the first

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Data Visualization | Learn SAS | Programming Tips

Rick WicklinAugust 24, 2022 0

How to stagger labels on an axis in PROC SGPLOT

A SAS programmer asked how to display long labels at irregular locations along the horizontal axis of scatter plot. The labels indicate various phases of a clinical study. This article discusses the problem and shows how to use the FITPOLICY=STAGGER option on the XAXIS or X2AXIS statement to avoid collisions

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Analytics | Learn SAS

Rick WicklinAugust 22, 2022 0

The univariate Box-Cox transformation

A SAS customer asked how to use the Box-Cox transformation to normalize a single variable. Recall that a normalizing transformation is a function that attempts to convert a set of data to be as nearly normal as possible. For positive-valued data, introductory statistics courses often mention the log transformation or

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Analytics | Learn SAS

Rick WicklinAugust 17, 2022 0

The Box-Cox transformation for a dependent variable in a regression

In the 1960s and '70s, before nonparametric regression methods became widely available, it was common to apply a nonlinear transformation to the dependent variable before fitting a linear regression model. This is still done today, with the most common transformation being a logarithmic transformation of the dependent variable, which fits

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