Centering a variable means that a constant has been subtracted from every value of a variable.  There are several ways that you can center variables.  For example, you could center…
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This is added immediately after the set statement, so that it is certain that SAS will encounter the length statement before it encounters any other mention of the variable.  The…
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Sometimes your research may predict that the size of a regression coefficient should be bigger for one group than for another. For example, you might believe that the regression coefficient…
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Given a dataset in which variables are measured within a given area (state, country, zip code, county), the data can be presented in a map. Proc gmap in SAS provides…
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When a data file has missing values, sometimes we may want to be able to distinguish between different types of missing values. For example, we can have missing values because…
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Sometimes part of the text on a plot may be too far from the plot or too close.  You can use the move option to move the text around.  Below…
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Specifying contrasts in logistic regression can be tricky.  The examples below will illustrate how to write contrast statements in proc logistic for increasingly complicated models.  All of our examples will…
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In order to help show the relationships among an OLS, random intercept, and random slope models this page shows a series of models each of which builds on the previous…
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You may also want to check out, FAQ: How do I use odds ratio to interpret logistic regression?, on our General FAQ page. Introduction Let’s begin with probability.  Let’s say…
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We will use the hsb2 dataset and start with a logistic regression model predicting the binary outcome variable hiread with the variables write and ses. The variable write is continuous,…
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