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Programming Tips

Schematic diagram of outliers in bivariate normal data. The point 'A' has large univariate z scores but a small Mahalanobis distance. The point 'B' has a large Mahalanobis distance. Only 'b' is a multivariate outlier.

Rick WicklinMarch 25, 2019 0

The geometry of multivariate versus univariate outliers

An important concept in multivariate statistical analysis is the Mahalanobis distance. The Mahalanobis distance provides a way to measure how far away an observation is from the center of a sample while accounting for correlations in the data. The Mahalanobis distance is a good way to detect outliers in multivariate

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Data Visualization | Programming Tips

Robert AllisonMarch 20, 2019 0

Is there more flooding than usual this year?

Flooding has been in the news the past few days, and that makes me want to analyze some data! I hang out at Jordan Lake (here in central North Carolina) a lot, so I decided to download the data for that lake, and do a graphical analysis. If you're interested

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Data for Good | Data Visualization | Programming Tips

Robert AllisonMarch 18, 2019 0

How deadly was the flu in 2019?

Here in the US, there's a lot of talk about the flu each year. First, people discuss whether or not to get the flu shot. Then there are discussions about whether or not you or your friends have the flu (or something else). Then the discussions about what strain of

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Programming Tips

Rick WicklinMarch 18, 2019 0

Interpolation vs extrapolation: the convex hull of multivariate data

Statisticians often emphasize the dangers of extrapolating from a univariate regression model. A common exercise in introductory statistics is to ask students to compute a model of population growth and predict the population far in the future. The students learn that extrapolating from a model can result in a nonsensical

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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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Data Visualization | Programming Tips

Robert AllisonMarch 14, 2019 0

US ethanol fuel production - a beautiful graph!

US farmers grow a lot of food ... but did you know some of them also grow fuel for our vehicles? Follow along and you'll learn how much fuel they grow, and also learn some tips about plotting this type of data! These days most gasoline in the US has

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Energy & Utilities

Programming Tips

Rick WicklinMarch 13, 2019 0

The value of pi depends on how you measure distance

It's time to celebrate Pi Day! Every year on March 14th (written 3/14 in the US), math-loving folks celebrate "all things pi-related" because 3.14 is the three-decimal approximation to the mathematical constant, π. Although children learn that pi is approximately 3.14159..., the actual definition of π is the ratio of

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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 | Data Visualization | Programming Tips

Robert AllisonMarch 7, 2019 0

Comparing child poverty around the world

According to the most recent data, the child poverty rate in China is 33.1% - the rate in Denmark is 2.9%. Where do other countries fall in between these two extremes? Let's build a graph and find out! (or, if you're not interested in the code - jump to the

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Programming Tips | SAS Administrators

Joe FurbeeMarch 6, 2019 0

Getting started with SAS Containers

As of December 2018, any customer with a valid SAS Viya order is able to package and deploy their SAS Viya software in Docker containers. SAS has provided a fully documented and supported project (or “recipe”) for easily building these containers. So how can you start? You can simply stop

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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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Data Visualization | Programming Tips

Robert AllisonFebruary 19, 2019 0

Graphing cardiovascular disease mortality data

I have written several blog posts about longevity, and here is another one related to that topic. Cardiovascular disease (cvd) is one of the more common causes of death, and I was wondering how those numbers have changed over time. Are fewer people dying from cvd, or are more people

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Programming Tips

Rick WicklinFebruary 18, 2019 0

An easier way to perform regression with restricted cubic splines in SAS

Maybe if we think and wish and hope and pray It might come true. Oh, wouldn't it be nice? The Beach Boys Months ago, I wrote about how to use the EFFECT statement in SAS to perform regression with restricted cubic splines. This is the modern way to use splines

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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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Data Visualization | Programming Tips

Robert AllisonFebruary 14, 2019 0

Analyzing age and gender distribution, with a pyramid chart

With the US census coming in 2020, I've decided to sharpen my skills at graphing census data. And today I'm working on creating a population pyramid chart to analyze the age and gender distribution. Follow along if you'd like to see how to create such a chart ... or jump

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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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Artificial Intelligence | Machine Learning | Programming Tips

Augusta ZhangFebruary 11, 2019 0

How to spot counterfeit company logos with AI – no SAS programming experience needed

As one of SAS' newest systems engineers, recently joining the Americas Artificial Intelligence Team, I’m incredibly excited to gain expertise in artificial intelligence and machine learning. I also look forward to applying my knowledge to enable others to leverage the advanced technologies that SAS offers. However, as a recent graduate

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Programming Tips

Chris Hemedinger

Chris HemedingerFebruary 8, 2019 0

Convert a text-based measurement to a number in SAS

Regular expressions are a powerful method for finding specific patterns in text. The syntax of regular expressions is intimidating, but once you've solved a few pattern-recognition problems with regex, you'll never go back to your old methods.

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Data Visualization | Programming Tips

Robert AllisonFebruary 8, 2019 0

How to show recessions on your SGplot line graph

Plotting just your data often helps you gain insight into how it has changed over time. But what if you want to know why it changed? Although correlation does not always imply causation, it is often useful to graph multiple things together, that might logically be related. For example, recessions

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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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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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Analytics | Data Visualization | Programming Tips | SAS Administrators | SAS Events

Frederik Vandenberghe

Frederik VandenbergheFebruary 1, 2019 0

Installing SAS Viya Azure virtual machines with a single click

I don't know about you, but when I read challenges like: Detecting hidden heart failure before it harms an individual Can SAS Viya AI help to digitalize pension management? How to recommend your next adventure based on travel data How to use advanced analytics in building a relevant next best

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Data Visualization | Programming Tips

Robert AllisonJanuary 31, 2019 0

Creating a fancy life expectancy chart, with SGplot

You might have noticed I've been trying out SAS ODS Graphics lately, whereas in the past I mainly used SAS/Graph for my samples. In this blog post I step you through my latest fancy SGplot graph - hopefully you'll learn some tips & techniques, as you follow along. (I don't

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Data Visualization | Programming Tips

Robert AllisonJanuary 29, 2019 0

Visualizing unemployment data, with a band plot

Many areas of the US are experiencing record low unemployment. This is great at the national level, and also great at a personal level (for example, I now have fewer unemployed friends asking to borrow money!) But just how low is the US unemployment rate, and how does it compare

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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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Analytics | Programming Tips

Rick WicklinJanuary 23, 2019 0

Coding and simulating categorical variables in regression models

Recently I was asked to explain the result of an ANOVA analysis that I posted to a statistical discussion forum. My program included some simulated data for an ANOVA model and a call to the GLM procedure to estimate the parameters. I was asked why the parameter estimates from PROC

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Analytics | Programming Tips

Rick WicklinJanuary 23, 2019 0

Coding and simulating categorical variables in regression models

Recently I was asked to explain the result of an ANOVA analysis that I posted to a statistical discussion forum. My program included some simulated data for an ANOVA model and a call to the GLM procedure to estimate the parameters. I was asked why the parameter estimates from PROC

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Analytics | Machine Learning | Programming Tips

Partition data into training, validation, and testing in SAS

Rick WicklinJanuary 21, 2019 0

Create training, validation, and test data sets in SAS

In machine learning and other model building techniques, it is common to partition a large data set into three segments: training, validation, and testing. Training data is used to fit each model. Validation data is a random sample that is used for model selection. These data are used to select

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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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Data Visualization | Programming Tips

Robert AllisonJanuary 17, 2019 0

Using International characters in a SAS graph

They say "The Sun never sets on the SAS Empire" ... and it's true! There are SAS users all over the world, and SAS output & results could be in any language. Therefore, if you're a SAS programmer, you might need to know how to create SAS graphs with international

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