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Analytics | Data Visualization | Learn SAS

Rick WicklinFebruary 25, 2019 0

Graphs of bootstrap statistics in PROC TTEST

When I run a bootstrap analysis, I create graphs to visualize the distribution of the bootstrap statistics. For example, in my article about how to bootstrap the difference of means in a two-sample t test, I included a histogram of the bootstrap distribution and added reference lines to indicate a

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Analytics | Learn SAS | Programming Tips

Rick WicklinFebruary 13, 2019 0

3 ways to obtain the Hessian at the MLE solution for a regression model

When you use maximum likelihood estimation (MLE) to find the parameter estimates in a generalized linear regression model, the Hessian matrix at the optimal solution is very important. The Hessian matrix indicates the local shape of the log-likelihood surface near the optimal value. You can use the Hessian to estimate

Analytics | Learn SAS

Rick WicklinFebruary 11, 2019 13

4 reasons to use PROC PLM for linear regression models in SAS

Have you ever run a regression model in SAS but later realize that you forgot to specify an important option or run some statistical test? Or maybe you intended to generate a graph that visualizes the model, but you forgot? Years ago, your only option was to modify your program

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Learn SAS | Programming Tips

Parameter estimates for synthetic (simulated) data that follows a regression model.

Rick WicklinJanuary 28, 2019 2

Simulate data for a regression model with categorical and continuous variables

This article shows how to use SAS to simulate data that fits a linear regression model that has categorical regressors (also called explanatory or CLASS variables). Simulating data is a useful skill for both researchers and statistical programmers. You can use simulation for answering research questions, but you can also

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Data Visualization | Learn SAS

Rick WicklinJanuary 14, 2019 2

How to align the Y and Y2 axes in PROC SGPLOT

When you overlay two series in PROC SGPLOT, you can either plot both series on the same axis or you can assign one series to the main axis (Y) and another to a secondary axis (Y2). If you use the Y and Y2 axes, they are scaled independently by default,

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Learn SAS | Programming Tips

Calibration plot for a misspecified logistic model

Rick WicklinJanuary 2, 2019 2

Top posts from The DO Loop in 2018

Last year, I wrote more than 100 posts for The DO Loop blog. Of these, the most popular articles were about data visualization, SAS programming tips, and statistical data analysis. Here are the most popular articles from 2018 in each category. Data Visualization Visualize repetition in song lyrics: In one

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Analytics | Data Visualization | Learn SAS

Rick WicklinDecember 17, 2018 0

Create a probability plot in SAS

Many data analysts use a quantile-quantile plot (Q-Q plot) to graphically assess whether data can be modeled by a probability distribution such as the normal, lognormal, or gamma distribution. You can use the QQPLOT statement in PROC UNIVARIATE to create a Q-Q plot for about a dozen common distributions. However,

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Analytics | Learn SAS | Programming Tips

Process flow diagram shows how to resample data to create a bootstrap distribution.

Rick WicklinDecember 12, 2018 8

The essential guide to bootstrapping in SAS

This article describes best practices and techniques that every data analyst should know before bootstrapping in SAS. The bootstrap method is a powerful statistical technique, but it can be a challenge to implement it efficiently. An inefficient bootstrap program can take hours to run, whereas a well-written program can give

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Data Visualization | Learn SAS

Rick WicklinDecember 10, 2018 1

Visualize Christmas songs

The best way to spread Christmas cheer is singing loud for all to hear! -Buddy in Elf In the Christmas movie Elf (2003), Jovie (played by Zooey Deschanel) must "spread Christmas cheer" to help Santa. She chooses to sing "Santa Claus is coming to town," and soon all of New

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Learn SAS | Programming Tips

Rick WicklinDecember 5, 2018 1

When is a histogram not a histogram? When it's a table!

Recently a SAS programmer wanted to obtain a table of counts that was based on a histogram. I showed him how you can use the OUTHIST= option on the HISTOGRAM statement in PROC UNIVARIATE to obtain that information. For example, the following call to PROC UNIVARIATE creates a histogram for

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