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Analytics | Learn SAS

Rick WicklinNovember 1, 2021 0

Fit a mixture of Weibull distributions in SAS

A previous article discusses how to use SAS regression procedures to fit a two-parameter Weibull distribution in SAS. The article shows how to convert the regression output into the more familiar scale and shape parameters for the Weibull probability distribution, which are fit by using PROC UNIVARIATE. Although PROC UNIVARIATE

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Analytics | Learn SAS

Rick WicklinOctober 27, 2021 0

Interpret estimates for a Weibull regression model in SAS

It can be frustrating when the same probability distribution has two different parameterizations, but such is the life of a statistical programmer. I previously wrote an article about the gamma distribution, which has two common parameterizations: one that uses a scale parameter (β) and another that uses a rate parameter

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Data for Good | Learn SAS

Álvaro LitránOctober 26, 2021 0

Ciencia de datos al servicio de la atención del paciente

Mejorar la vida de las personas gracias a los datos es uno de nuestros propósitos en SAS. Por eso, una de las categorías de los premios Curiosity Data Science Iberian Awards, que hemos organizado este año por primera vez junto a SPAIN AI y la Asociación Portuguesa de Ciencia de

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Analytics | Learn SAS

Rick WicklinOctober 20, 2021 0

An introduction to genetic algorithms in SAS

A genetic algorithm (GA) is a heuristic optimization technique. The method tries to mimic natural selection and evolution by starting with a population of random candidates. Candidates are evaluated for "fitness" by plugging them into the objective function. The characteristics of the better candidates are combined to create a new

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Data Management | Learn SAS | Programming Tips

Leonid BatkhanOctober 14, 2021 0

Introducing TRIMS function to remove any leading and/or trailing characters from SAS strings

Leonid Batkhan introduces multipurpose TRIMS function that removes any leading, trailing or both leading and trailing characters from SAS strings.

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Learn SAS

Rick WicklinOctober 11, 2021 0

The knapsack problem: Binary integer programming in SAS/IML

Many optimization problems in statistics and machine learning involve continuous parameters. For example, maximum likelihood estimation involves optimizing a log-likelihood function over a continuous domain, possibly with constraints. Recently, however, I had to solve an optimization problem for which the solution vector was a 0/1 binary variable. To solve the

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Learn SAS

Álvaro LitránOctober 7, 2021 0

Optimización de la escritura de correos electrónicos con análisis estilométrico

Carlos Moreno Morera es el ganador Gold de la categoría Data4Innovation de los premios Curiosity Data Science Iberian Awards, que hemos organizado este año por primera vez desde SAS, junto a SPAIN AI y la Asociación Portuguesa de Ciencia de Datos (DSPA). Originario de Santa Cruz de Tenerife, Carlos es

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Learn SAS | Programming Tips

Rick WicklinOctober 6, 2021 0

Logical negation of vectors

In a matrix-vector language such as SAS/IML, it is useful to always remember that the fundamental objects are matrices and that all operations are designed to work on matrices. (And vectors, which are matrices that have only one row or one column.) By using matrix operations, you can often eliminate

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Analytics | Learn SAS

Rick WicklinOctober 4, 2021 0

Choose samples with specified statistical properties

A reader asked whether it is possible to find a bootstrap sample that has some desirable properties. I am using the term "bootstrap sample" to refer to the result of randomly resampling with replacement from a data set. Specifically, he wanted to find a bootstrap sample that has a specific

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Learn SAS | Programming Tips

SAS JediSeptember 30, 2021 0

Jedi SAS Tricks: 5 Ways to Make Your SAS Code Run Faster

Tired of waiting for answers? Then make your SAS code run faster with these 5 tips.

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Learn SAS

Álvaro LitránSeptember 28, 2021 0

IA para un sector minero más productivo, sostenible y seguro

La curiosidad juega un papel primordial en la ciencia de datos, así como en la cultura de SAS. Y para reconocer su valor, este año hemos organizado por primera vez los premios Curiosity Data Science Iberian Awards, en colaboración con SPAIN AI y la Asociación Portuguesa de Ciencia de Datos

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Data Visualization | Learn SAS

Rick WicklinSeptember 27, 2021 0

Why you should visualize distributions instead of report means

Graphing data is almost always more informative than displaying a table of summary statistics. In a recent article about "dynamite plots," I briefly mentioned that graphs such as box plots and strip plots are better at showing data than graphs that merely show the mean and standard deviation. This article

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Analytics | Learn SAS | Programming Tips

Rick WicklinSeptember 22, 2021 0

Use simulations to evaluate the accuracy of asymptotic results

The field of probability and statistics is full of asymptotic results. The Law of Large Numbers and the Central Limit Theorem are two famous examples. An asymptotic result can be both a blessing and a curse. For example, consider a result that says that the distribution of some statistic converges

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Learn SAS | Programming Tips

Rick WicklinSeptember 20, 2021 0

Add an item to a sublist

The SAS/IML language supports lists, which are containers that store other objects, such as matrices and other lists. A primary use of lists is to pack objects of various types into a single symbol that can be passed to and from modules. A useful feature of using lists is that

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Analytics | Learn SAS | Programming Tips

Rick WicklinSeptember 15, 2021 0

The partition problem: An optimization approach

I previously wrote about one way to solve the partition problem in SAS. In the partition problem, you divide (or partition) a set of N items into two groups of size k and N-k such that the sum of the items' weights is the same in each group. For example,

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Learn SAS | Programming Tips | Students & Educators

Suzanne MorgenSeptember 13, 2021 0

Top Books for SAS Programmers

The Day of the Programmer is not enough time to celebrate our favorite code-creators. That’s why at SAS, we celebrate an entire week with SAS Programmer Week! If you want to extend the fun and learning of SAS Programmer Week year-round, SAS Press is here to support you with books

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Analytics | Learn SAS | Programming Tips

Rick WicklinSeptember 13, 2021 0

The partition problem

The partition problem has many variations, but recently I encountered it as an interactive puzzle on a computer. (Try a similar game yourself!) The player is presented with an old-fashioned pan-balance scale and a set of objects of different weights. The challenge is to divide (or partition) the objects into

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Analytics | Data Visualization | Learn SAS

Rick WicklinSeptember 9, 2021 0

Simulate proportions for groups

A statistical programmer asked how to simulate event-trials data for groups. The subjects in each group have a different probability of experiencing the event. This article describes one way to simulate this scenario. The simulation is similar to simulating from a mixture distribution. This article also shows three different ways

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Learn SAS | Programming Tips

Leonid BatkhanSeptember 2, 2021 0

Removing trailing characters from SAS strings

SAS' Leonid Batkhan shows how to cut away ANY unwanted trailing characters (not just blanks) from SAS text strings to clean up your data.

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Learn SAS | Programming Tips

Rick WicklinAugust 25, 2021 0

Convert a symmetric matrix from wide to long form

For graphing multivariate data, it is important to be able to convert the data between "wide form" (a separate column for each variable) and "long form" (which contains an indicator variable that assigns a group to each observation). If the data are numeric, the wide data can be represented as

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Analytics | Data Visualization | Learn SAS

Harry SnartAugust 23, 2021 0

Understanding your data: Visual Exploratory Data Analysis

In our previous section of the series we discussed the impact of missingness and techniques to address this. In this final section of the series we look at how we can use drag-and-drop tools to accelerate our EDA. As mentioned at the beginning of this series, SAS Viya offers multiple

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Learn SAS | Programming Tips

Leonid BatkhanAugust 23, 2021 0

Removing leading characters from SAS strings

SAS' Leonid Batkhan shows you how to remove ANY leading characters (not just blanks) from text strings to tidy up your data.

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Data Visualization | Learn SAS

Rick WicklinAugust 18, 2021 0

A comparison of different weighting schemes for ranking sports teams

A previous article discusses the geometry of weighted averages and shows how choosing different weights can lead to different rankings of the subjects. As an example, I showed how college programs might rank applicants by using a weighted average of factors such as test scores. "The best" applicant is determined

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Analytics | Data for Good | Learn SAS

Alex CoopAugust 17, 2021 0

Canadian nonprofit meets employer demands with SAS training

Fueled by a number of factors, including a global pandemic, data analytics skills are in high-demand. Organizations like the Youth Employment Services (YES) are well aware of the abundance of data and its growing complexity. That's why they partnered with SAS last year to provide free learning pathways to help

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Advanced Analytics | Analytics | Data Visualization | Learn SAS

Harry SnartAugust 16, 2021 0

Understanding your data: Missing at random versus missing not at random

In our last blog we explored the potential impact of missingness in data in terms of its impact on models which require complete case analysis. We took a simple view that data was missing with an equal, independent, probability for any given model input. This week we explore cases where

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Learn SAS | Programming Tips

Rick WicklinAugust 11, 2021 0

More on the SWEEP operator for least-square regression models

One of the benefits of using the SWEEP operator is that it enables you to "sweep in" columns (add effects to a model) in any order. This article shows that if you use the SWEEP operator, you can compute a SSCP matrix and use it repeatedly to estimate any linear

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Advanced Analytics | Analytics | Data Visualization | Learn SAS

Harry SnartAugust 9, 2021 0

Understanding your data: Assessing the impact of missingness and dimensionality

In the previous section of this series we discussed ways of assessing the relationship between variables. This week we change the focus to the shape and sparsity of our dataset. One area of Explanatory Data Analysis which we’ve missed so far is the impact of missingness in data. Having missing

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Learn SAS | Programming Tips

Rick WicklinAugust 9, 2021 0

Never multiply with a large permutation matrix

Do you ever use a permutation matrix to change the order of rows or columns in a matrix? Did you know that there is a more efficient way in matrix-oriented languages such as SAS/IML, MATLAB, and R? Remember the following tip: Never multiply with a large permutation matrix! Instead, use

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Analytics | Learn SAS

students in front of computer, students learning

Lynn LetukasAugust 4, 2021 0

What are the best skills for adults going 'back to school'?

The predicted “Great Resignation” is underway, with the US Labor Department reporting people quitting jobs in record numbers, with 4 million doing so in April alone. At the same time, companies are expected to step up hiring, with 77 percent of executives in a recent poll claiming they plan to

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Data Visualization | Learn SAS

Rick WicklinAugust 4, 2021 0

Use SAS to create mathematical art

In a previous article, I discussed a beautiful painting called "Phantom’s Shadow, 2018" by the Nigerian-born artist, Odili Donald Odita. I noted that if you overlay a 4 x 4 grid on the painting, then each cell contains a four-bladed pinwheel shape. The cells display rotations and reflections of the pinwheel. The

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