Blog Archives

In praise of simple graphics

June 27, 2016
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In praise of simple graphics

'Tis a gift to be simple. -- Shaker hymn In June 2015 I published a short article for Significance, a magazine that features statistical and data-related articles that are of general interest to a wide a range of scientists. The title of my article is "In Praise of Simple Graphics." […] The post In praise of simple graphics appeared first on The DO Loop.

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Use the EFFECTPLOT statement to visualize regression models in SAS

June 22, 2016
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Use the EFFECTPLOT statement to visualize regression models in SAS

Graphs enable you to visualize how the predicted values for a regression model depend on the model effects. You can gain an intuitive understanding of a model by using the EFFECTPLOT statement in SAS to create graphs like the one shown at the top of this article. Many SAS regression […] The post Use the EFFECTPLOT statement to visualize regression models in SAS appeared first on The DO Loop.

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The SELECT statement in the SAS DATA step

June 20, 2016
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The SELECT statement in the SAS DATA step

Every beginning SAS programmer learns the simple IF-THEN/ELSE statement for conditional processing in the SAS DATA step. The basic If-THEN statement handles two cases: if a condition is true, the program does one thing, otherwise the program does something else. Of course, you can handle more cases by using multiple […] The post The SELECT statement in the SAS DATA step appeared first on The DO Loop.

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Overlay plots on a box plot in SAS: Continuous X axis

June 15, 2016
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Overlay plots on a box plot in SAS: Continuous X axis

I have previously shown how to overlay basic plots on box plots when all plots share a common discrete X axis. It is interesting to note that box plots can also be overlaid on a continuous (interval) axis. You often need to bin the data before you create the plot. […] The post Overlay plots on a box plot in SAS: Continuous X axis appeared first on The DO Loop.

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Overlay plots on a box plot in SAS: Discrete X axis

June 13, 2016
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Overlay plots on a box plot in SAS: Discrete X axis

Box plots summarize the distribution of a continuous variable. You can display multiple box plots in a single graph by specifying a categorical variable. The resulting graph shows the distribution of subpopulations, such as different experimental groups. In the SGPLOT procedure, you can use the CATEGORY= option on the VBOX […] The post Overlay plots on a box plot in SAS: Discrete X axis appeared first on The DO Loop.

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Lasagna plots in SAS: When spaghetti plots don’t suffice

June 8, 2016
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Lasagna plots in SAS: When spaghetti plots don’t suffice

Last week I discussed how to create spaghetti plots in SAS. A spaghetti plot is a type of line plot that contains many lines. Spaghetti plots are used in longitudinal studies to show trends among individual subjects, which can be patients, hospitals, companies, states, or countries. I showed ways to […] The post Lasagna plots in SAS: When spaghetti plots don't suffice appeared first on The DO Loop.

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How to write CONTRAST and ESTIMATE statements in SAS regression procedures

June 6, 2016
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How to write CONTRAST and ESTIMATE statements in SAS regression procedures

I got several positive comments about a recent tip, "How to fit a variety of logistic regression models in SAS." A reader asked if I knew any other similar resources about statistical analysis in SAS. Absolutely! One gem that comes to mind is "Examples of writing CONTRAST and ESTIMATE statements." […] The post How to write CONTRAST and ESTIMATE statements in SAS regression procedures appeared first on The DO Loop.

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Create spaghetti plots in SAS

June 2, 2016
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Create spaghetti plots in SAS

What is a spaghetti plot? Spaghetti plots are line plots that involve many overlapping lines. Like spaghetti on your plate, they can be hard to unravel, yet for many analysts they are a delicious staple of data visualization. This article presents the good, the bad, and the messy about spaghetti […] The post Create spaghetti plots in SAS appeared first on The DO Loop.

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Grids and linear subspaces

May 31, 2016
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Grids and linear subspaces

A grid is a set of evenly spaced points. You can use SAS to create a grid of points on an interval, in a rectangular region in the plane, or even in higher-dimensional regions like the parallelepiped shown at the left, which is generated by three vectors. You can use […] The post Grids and linear subspaces appeared first on The DO Loop.

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Compute the square root matrix

May 25, 2016
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Compute the square root matrix

Children in primary school learn that every positive number has a real square root. The number x is a square root of s, if x2 = s. Did you know that matrices can also have square roots? For certain matrices S, you can find another matrix X such that X*X […] The post Compute the square root matrix appeared first on The DO Loop.

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