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Learn SAS

Learn about the latest tips, tutorials, upcoming events and certifications

Learn SAS | Programming Tips

Rick WicklinApril 8, 2019 0

Use the FLOOR-MOD trick to allocate items to groups

Suppose you need to assign 100 patients equally among 3 treatment groups in a clinical study. Obviously, an equal allocation is impossible because the second number does not evenly divide the first, but you can get close by assigning 34 patients to one group and 33 to the others. Mathematically,

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Data Visualization | Learn SAS | SAS Events

Scott HicksApril 8, 2019 0

Why Maps matter: Lessons learned from London's 1854 Cholera outbreak

The catch phrase “everything happens somewhere” is increasingly common these days. That “somewhere” translates into a location on the Earth; a latitude and longitude. When one of these “somewhere’s” is combined with many other “somewhere’s”, you quickly have a robust spatial data set that becomes actionable with the right analytic

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Learn SAS | Programming Tips

Rick WicklinApril 3, 2019 0

Convergence in mixed models: When the estimated G matrix is not positive definite

I've previously written about how to deal with nonconvergence when fitting generalized linear regression models. Most generalized linear and mixed models use an iterative optimization process, such as maximum likelihood estimation, to fit parameters. The optimization might not converge, either because the initial guess is poor or because the model

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Learn SAS | Programming Tips

Rick WicklinApril 1, 2019 0

Matrix operations and BY groups

Many SAS procedures support the BY statement, which enables you to perform an analysis for subgroups of the data set. Although the SAS/IML language does not have a built-in "BY statement," there are various techniques that enable you to perform a BY-group analysis. The two I use most often are

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Data Visualization | Learn SAS

Scott HicksMarch 27, 2019 0

Creating custom region maps with SAS Visual Analytics

SAS Visual Analytics supports region maps for Country, US states, and provinces out-of-the-box. These work well for small scale maps covering the world, a continent, or a single country. However, other regions are often needed. Beginning in version 8.3, VA supports custom polygons to display regions such as sales territories,

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Data Visualization | Learn SAS

Rick WicklinMarch 20, 2019 0

Truncate response surfaces

An analyst was using SAS to analyze some data from an experiment. He noticed that the response variable is always positive (such as volume, size, or weight), but his statistical model predicts some negative responses. He posted the data and asked if it is possible to modify the graph so

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Data Visualization | Learn SAS | Programming Tips

Martin MinceyMarch 15, 2019 0

How to view or create ODS output without causing SAS® to stop responding or run slowly

SAS makes it easy for you to create a large amount of procedure output with very few statements. However, when you create a large amount of procedure output with the Output Delivery System (ODS), your SAS session might stop responding or run slowly. In some cases, SAS generates a “Not

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Learn SAS | Programming Tips

Rick WicklinMarch 11, 2019 0

How to detect SAS data sets that contain (or do not contain) character variables

A SAS programmer posted an interesting question on a SAS discussion forum. The programmer wanted to iterate over hundreds of SAS data sets, read in all the character variables, and then do some analysis. However, not every data set contains character variables, and SAS complains when you ask it to

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Data for Good | Learn SAS | Students & Educators

Sian RobertsMarch 7, 2019 0

Breaking down walls for science: SAS Press donates books to the world’s largest research methods library

In a move to combat "stataphobia" and foster excellence in statistics in developing countries, SAS Press last month donated 70 SAS Press titles to the Serageldin Research Library at the Library of Alexandria in Egypt. The library’s mission is to achieve statistical equity so that a student in Chad has

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Data Visualization | Learn SAS

Rick WicklinMarch 6, 2019 0

Use PROC BOXPLOT to display hundreds of box plots

A previous article shows how to use a scatter plot to visualize the average SAT scores for all high schools in North Carolina. The schools are grouped by school districts and ranked according to the median value of the schools in the district. For the school districts that have many

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Learn SAS | Programming Tips

Leonid BatkhanMarch 5, 2019 0

How to conditionally terminate a SAS batch flow process in UNIX/Linux

In automated production (or business operations) environments, we often run SAS job flows in batch mode and on schedule. SAS job flow is a collection of several inter-dependent SAS programs executed as a single process. In my earlier posts, Running SAS programs in batch under Unix/Linux and Let SAS write

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Learn SAS

Shelley Sessoms

Shelley SessomsFebruary 27, 2019 0

We’re moving on: SAS Learning Post has merged with SAS Users

The SAS Learning post has merged with the SAS Users blog to provide you with all the training, certification, books, events, and programming tips you need.

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Data Visualization | Learn SAS

Scott HicksFebruary 27, 2019 0

Using Custom Coordinates for map creation in SAS Visual Analytics

In this post, we continue our discussion of geography variables, the foundation of Visual Analytics Geo maps. This time we will look at Custom Coordinates. As with any statistical graph, understanding your data is key. But when using Custom Coordinates for geographic maps, this understanding becomes even more important. Use

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Data Visualization | Learn SAS

Rick WicklinFebruary 27, 2019 0

3 ways to create nested box plots in SAS

Box plots are a great way to compare the distributions of several subpopulations of your data. For example, box plots are often used in clinical studies to visualize the response of patients in various cohorts. This article describes three techniques to visualize responses when the cohorts have a nested or

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Analytics | Data Visualization | Learn SAS

Rick WicklinFebruary 25, 2019 0

Graphs of bootstrap statistics in PROC TTEST

When I run a bootstrap analysis, I create graphs to visualize the distribution of the bootstrap statistics. For example, in my article about how to bootstrap the difference of means in a two-sample t test, I included a histogram of the bootstrap distribution and added reference lines to indicate a

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Learn SAS

Samantha Gidlow

Samantha GidlowFebruary 22, 2019 0

Thinking about getting SAS® certified? Check out the new SAS certification guide!

Find out about the new SAS Certified Specialist credential, and all the ways you can prepare for it.

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Data Visualization | Learn SAS | Programming Tips

Martin MinceyFebruary 15, 2019 0

Embed scalable graphics using the ODS HTML5 destination

Beginning with SAS® 9.4, you can embed graphics output within HTML output using the ODS HTML5 destination. This technique works with SAS/GRAPH® procedures (such as GPLOT and GCHART), SG procedures (such as SGPLOT and SGRENDER), and when you create graphics output with ODS Graphics enabled. Most (if not all) existing

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Learn SAS

Mark StevensFebruary 13, 2019 0

New Performance-Based Certification: Write SAS Code During Your Exam

SAS has worked with our exam delivery partners to integrate a live lab into an exam, which can be delivered anywhere, anytime, on-demand.

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Analytics | Learn SAS | Programming Tips

Rick WicklinFebruary 13, 2019 0

3 ways to obtain the Hessian at the MLE solution for a regression model

When you use maximum likelihood estimation (MLE) to find the parameter estimates in a generalized linear regression model, the Hessian matrix at the optimal solution is very important. The Hessian matrix indicates the local shape of the log-likelihood surface near the optimal value. You can use the Hessian to estimate

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Learn SAS

Sian RobertsFebruary 12, 2019 0

Isn’t SAS Romantic?

SAS Press gets in the Valentine's Day spirit.

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Analytics | Learn SAS

Rick WicklinFebruary 11, 2019 0

4 reasons to use PROC PLM for linear regression models in SAS

Have you ever run a regression model in SAS but later realize that you forgot to specify an important option or run some statistical test? Or maybe you intended to generate a graph that visualizes the model, but you forgot? Years ago, your only option was to modify your program

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Data Visualization | Learn SAS

Scott HicksFebruary 8, 2019 0

Fundamentals of SAS Visual Analytics geo maps

Creating a map with SAS Visual Analytics begins with the geographic variable. This blog post explains the first type of geography variable that VA supports: predefined. Future posts will cover the other two types of geography variables in VA: custom coordinates and custom polygons.

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Data Management | Learn SAS | Programming Tips

Leonid BatkhanFebruary 6, 2019 0

How to split a raw file or a data set into many external raw files

Recently, I worked on a cybersecurity project that entailed processing a staggering number of raw text files about web traffic. Millions of rows had to be read and parsed to extract variable values. The problem was complicated by the varying records composition. Each external raw file was a collection of

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Learn SAS

K. Matthew Windham

K. Matthew WindhamFebruary 5, 2019 0

Webpage scraping made easy with PROC HTTP

SAS Press author Matt Windham shows you how to use the SAS procedure PROC HTTP to grab raw data from a website.

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Data Visualization | Learn SAS | Programming Tips

SGMAP using DENSITY=3

Kelly MillsFebruary 4, 2019 0

Use PROC GREMOVE and GREDUCE for Nice SGMAP Regions

In the previous Graphically Speaking blog for PROC SGMAP, you used PROC GPROJECT so map regions would match OpenStreetMap and Esri background images. This time, the same British Columbia shapefile is used with: PROC GREMOVE to remove unwanted boundary lines PROC GREDUCE to reduce map data PROC GPROJECT to zoom

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Learn SAS | Programming Tips

Parameter estimates for synthetic (simulated) data that follows a regression model.

Rick WicklinJanuary 28, 2019 0

Simulate data for a regression model with categorical and continuous variables

This article shows how to use SAS to simulate data that fits a linear regression model that has categorical regressors (also called explanatory or CLASS variables). Simulating data is a useful skill for both researchers and statistical programmers. You can use simulation for answering research questions, but you can also

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Learn SAS

Michelle HomesJanuary 24, 2019 0

SAS Press books changed my life story!

Michelle Homes explains how SAS Press books changed her life, and how she donates her books and time to the SAS community whenever she can.

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Learn SAS

Suzanne MorgenJanuary 22, 2019 0

Secrets from a SAS Expert: An Interview with Leonid Batkhan

You’re probably already familiar with Leonid Batkhan from his popular blog right here on The Learning Post. In fact, he’s one of our most engaging authors, with thousands of views and hundreds of comments. Leonid is a true SAS Sensei. He has been at SAS for nearly 25 years and

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Learn SAS | Programming Tips

Kathryn McLawhornJanuary 18, 2019 0

Navigating SAS documentation to find out about new, modified, and updated features

Learn about the latest product features, changes and upgrade information in new sections of SAS product documentation for SAS® 9.4 and SAS® Viya®. SAS' Kathryn McLawhorn tells us all about them.

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