The DO Loop

Data Visualization

Get the right information, with visual impact, to the people who need it

Analytics | Data Visualization | Learn SAS

Rick WicklinJune 17, 2019 11

Influential observations in a linear regression model: The DFBETAS statistics

My article about deletion diagnostics investigated how influential an observation is to a least squares regression model. In other words, if you delete the i_th observation and refit the model, what happens to the statistics for the model? SAS regression procedures provide many tables and graphs that enable you to

English

Data Visualization | Learn SAS | Programming Tips

Rick WicklinJune 5, 2019 2

Plot a family of curves in SAS

A family of curves is generated by an equation that has one or more parameters. To visualize the family, you might want to display a graph that overlays four of five curves that have different parameter values, as shown to the right. The graph shows members of a family of

English

Data Visualization | Learn SAS | Programming Tips

Rick WicklinJune 3, 2019 4

Graph wide data and long data in SAS

Statistical programmers and analysts often use two kinds of rectangular data sets, popularly known as wide data and long data. Some analytical procedures require that the data be in wide form; others require long form. (The "long format" is sometimes called "narrow" or "tall" data.) Fortunately, the statistical graphics procedures

English

Analytics | Data Visualization | Learn SAS

Rick WicklinMay 30, 2019 10

Visualize interaction effects in regression models

Knowing how to visualize a regression model is a valuable skill. A good visualization can help you to interpret a model and understand how its predictions depend on explanatory factors in the model. Visualization is especially important in understanding interactions between factors. Recently I read about work by Jacob A.

English

Analytics | Data Visualization

Rick WicklinMay 22, 2019 1

Gershgorin discs and the location of eigenvalues

The eigenvalues of a matrix are not easy to compute. It is remarkable, therefore, that with relatively simple mental arithmetic, you can obtain bounds for the eigenvalues of a matrix of any size. The bounds are provided by using a marvelous mathematical result known as Gershgorin's Disc Theorem. For certain

English

Analytics | Data Visualization

Rick WicklinMarch 27, 2019 2

How to simulate multivariate outliers

In simulation studies, sometimes you need to simulate outliers. For example, in a simulation study of regression techniques, you might want to generate outliers in the explanatory variables to see how the technique handles high-leverage points. This article shows how to generate outliers in multivariate normal data that are a

English

Data Visualization | Learn SAS

Rick WicklinMarch 20, 2019 2

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

English

Data Visualization | Learn SAS

Rick WicklinMarch 6, 2019 3

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

English

Analytics | Data Visualization

Rick WicklinMarch 4, 2019 1

Visualize SAT scores in North Carolina

Standardized tests like the SAT and ACT can cause stress for both high school students and their parents, but according to a Wall Street Journal article, the SAT and ACT "provide an invaluable measure of how students are likely to perform in college and beyond." Naturally, students wonder how their

English

Data Visualization | Learn SAS

Rick WicklinFebruary 27, 2019 4

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

English

Blogs

Blogs

Data Visualization