SAS

Blogs on the SAS software

The diffogram and other graphs for multiple comparisons of means

October 18, 2017
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The diffogram and other graphs for multiple comparisons of means

In a previous article, I discussed the lines plot for multiple comparisons of means. Another graph that is frequently used for multiple comparisons is the diffogram, which indicates whether the pairwise differences between means of groups are statistically significant. This article discusses how to interpret a diffogram. Two related plots [...] The post The diffogram and other graphs for multiple comparisons of means appeared first on The DO Loop.

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Graphs for multiple comparisons of means: The lines plot

October 16, 2017
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Graphs for multiple comparisons of means: The lines plot

Last week Warren Kuhfeld wrote about a graph called the "lines plot" that is produced by SAS/STAT procedures in SAS 9.4M5. (Notice that the "lines plot" has an 's'; it is not a line plot!) The lines plot is produced as part of an analysis that performs multiple comparisons of [...] The post Graphs for multiple comparisons of means: The lines plot appeared first on The DO Loop.

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Simulate correlations by using the Wishart distribution

October 11, 2017
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Simulate correlations by using the Wishart distribution

The article "Fisher's transformation of the correlation coefficient" featured a Monte Carlo simulation that generated sample correlations from bivariate normal data. The simulation used three steps: Simulate B samples of size N from a bivariate normal distribution with correlation ρ. Use PROC CORR to compute the sample correlation matrix for [...] The post Simulate correlations by using the Wishart distribution appeared first on The DO Loop.

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Order correlations by magnitude

October 9, 2017
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Order correlations by magnitude

Correlations between variables are typically displayed in a matrix. Because the correlation matrix is determined by the order of the variables, it is difficult to find the largest and smallest correlations, which is why analysts sometimes use colors to visualize the correlation matrix. Another visualization option is the pairwise correlation [...] The post Order correlations by magnitude appeared first on The DO Loop.

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Create and interpret a weighted histogram

October 4, 2017
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Create and interpret a weighted histogram

If you perform a weighted statistical analysis, it can be useful to produce a statistical graph that also incorporates the weights. This article shows how to construct and interpret a weighted histogram in SAS. How to construct a weighted histogram Before constructing a weighted histogram, let's review the construction of [...] The post Create and interpret a weighted histogram appeared first on The DO Loop.

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How to understand weight variables in statistical analyses

October 2, 2017
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How to understand weight variables in statistical analyses

How can you specify weights for a statistical analysis? Hmmm, that's a "weighty" question! Many people on discussion forums ask "What is a weight variable?" and "How do you choose a weight for each observation?" This article gives a brief overview of weight variables in statistics and includes examples of [...] The post How to understand weight variables in statistical analyses appeared first on The DO Loop.

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Data-driven simulation

September 27, 2017
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Data-driven simulation

In a large simulation study, it can be convenient to have a "control file" that contains the parameters for the study. My recent article about how to simulate multivariate normal clusters demonstrates a simple example of this technique. The simulation in that article uses an input data set that contains [...] The post Data-driven simulation appeared first on The DO Loop.

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Simulate multivariate normal data in SAS by using PROC SIMNORMAL

September 25, 2017
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Simulate multivariate normal data in SAS by using PROC SIMNORMAL

My article about Fisher's transformation of the Pearson correlation contained a simulation. The simulation uses the RANDNORMAL function in SAS/IML software to simulate multivariate normal data. If you are a SAS programmer who does not have access to SAS/IML software, you can use the SIMNORMAL procedure in SAS/STAT software to [...] The post Simulate multivariate normal data in SAS by using PROC SIMNORMAL appeared first on The DO Loop.

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ggformula: another option for teaching graphics in R to beginners

September 21, 2017
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ggformula: another option for teaching graphics in R to beginners

A previous entry (http://sas-and-r.blogspot.com/2017/07/options-for-teaching-r-to-beginners.html) describes an approach to teaching graphics in R that also “get[s] students doing powerful things quickly”, as David Robinson suggested. In t...

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ggformula: another option for teaching graphics in R to beginners

September 21, 2017
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ggformula: another option for teaching graphics in R to beginners

A previous entry (http://sas-and-r.blogspot.com/2017/07/options-for-teaching-r-to-beginners.html) describes an approach to teaching graphics in R that also “get[s] students doing powerful things quickly”, as David Robinson suggested. In t...

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