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Data Visualization

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Rick WicklinSeptember 27, 2021 4

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 | 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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Data Visualization

Rick WicklinSeptember 7, 2021 5

Remaking a panel of dynamite plots

A colleague spent a lot of time creating a panel of graphs to summarize some data. She did not use SAS software to create the graph, but I used SAS to create a simplified version of her graph, which is shown to the right. (The colors are from her graph.)

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Analytics | Data Visualization | Programming Tips

Rick WicklinAugust 23, 2021 1

Sliced survival graphs in SAS

This article shows how to create a "sliced survival plot" for proportional-hazards models that are created by using PROC PHREG in SAS. Graphing the result of a statistical regression model is a valuable way to communicate the predictions of the model. Many SAS procedures use ODS graphics to produce graphs

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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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Data Visualization | Learn SAS

Rick WicklinAugust 4, 2021 3

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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Analytics | Data Visualization | Programming Tips

Rick WicklinJuly 19, 2021 1

Copulas and multivariate distributions with normal marginals

After my recent articles on simulating data by using copulas, many readers commented about the power of copulas. Yes, they are powerful, and the geometry of copulas is beautiful. However, it is important to be aware of the limitations of copulas. This article creates a bizarre example of bivariate data,

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Analytics | Data Visualization

Rick WicklinJune 16, 2021 3

The geometry of the Iman-Conover transformation

A previous article showed how to simulate multivariate correlated data by using the Iman-Conover transformation (Iman and Conover, 1982). The transformation preserves the marginal distributions of the original data but permutes the values (columnwise) to induce a new correlation among the variables. When I first read about the Iman-Conover transformation,

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Data Visualization | Learn SAS

Rick WicklinApril 14, 2021 8

Overlay other graphs on a bar chart with PROC SGPLOT

It can be frustrating to receive an error message from statistical software. In the early days of the SAS statistical graphics (SG) procedures, an error message that I dreaded was ERROR: Attempting to overlay incompatible plot or chart types. This error message appears when you attempt to use PROC SGPLOT

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Data Visualization | Learn SAS

Rick WicklinApril 12, 2021 8

3 reasons to prefer a horizontal bar chart

Most introductory statistics courses introduce the bar chart as a way to visualize the frequency (counts) for a categorical variable. A vertical bar chart places the categories along the horizontal (X) axis and shows the counts (or percentages) on the vertical (Y) axis. The vertical bar chart is a precursor

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