The DO Loop

Data Visualization

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Rick WicklinDecember 13, 2021 5

A principal component analysis of color palettes

In a previous article, I visualized seven Christmas-themed palettes of colors, as shown to the right. You can see that the palettes include many red, green, and golden colors. Clearly, the colors in the Christmas palettes are not a random sample from the space of RGB colors. Rather, they represent

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Data Visualization | Learn SAS

Rick WicklinDecember 8, 2021 4

Visualize palettes of colors in SAS

In data visualization, colors can represent the values of a variable in a choropleth map, a heatmap, or a scatter plot. But how do you visualize a palette of colors from the RGB or hexadecimal values of the colors? One way is to use the HEATMAPDISC subroutine in SAS/IML, which

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Data Visualization | Programming Tips

Rick WicklinNovember 17, 2021 0

The order of vertices on a convex polygon

In a previous article, I showed how to use theCVEXHULL function in SAS/IML to compute the convex hull of a finite set of planar points. The convex hull is a convex polygon, which is defined by its vertices. To visualize the polygon, you need to know the vertices in sequential

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Data Visualization | Learn SAS | Programming Tips

Rick WicklinNovember 15, 2021 10

Two-dimensional convex hulls in SAS

Given a cloud of points in the plane, it can be useful to identify the convex hull of the points. The convex hull is the smallest convex set that contains the observations. For a finite set of points, it is a convex polygon that has some of the points as

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Data Visualization | Learn SAS

Rick WicklinNovember 10, 2021 2

Create a frequency polygon in SAS

I was recently asked how to create a frequency polygon in SAS. A frequency polygon is an alternative to a histogram that shows similar information about the distribution of univariate data. It is the piecewise linear curve formed by connecting the midpoints of the tops of the bins. The graph

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Analytics | Data Visualization

Rick WicklinNovember 8, 2021 0

The normal approximation and random samples of the binomial distribution

Recall that the binomial distribution is the distribution of the number of successes in a set of independent Bernoulli trials, each having the same probability of success. Most introductory statistics textbooks discuss the approximation of the binomial distribution by the normal distribution. The graph to the right shows that the

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Data Visualization | Learn SAS

Rick WicklinNovember 3, 2021 6

Add reference lines to a bar chart in SAS

A SAS programmer asked whether it is possible to add reference lines to the categorical axis of a bar chart. The answer is yes. You can use the VBAR statement, but I prefer to use the VBARBASIC (or VBARPARM) statement, which enables you to overlay a wide variety of graphs

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Data Visualization | Learn SAS

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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