Say that you want to look at the relationship between how much a child talks on the phone and the age of the child. You get a random sample of…
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String processing is fairly easy in Stata because of the many built-in string functions. Among these string functions are three functions that are related to regular expressions, regexm for matching,…
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Credits This page was developed and written by Karla Lindquist, Senior Statistician in the Division of Geriatrics at UCSF. We are very grateful to Karla for taking the time to…
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Some Stata users have found that there are values of e(r2) and e(r2_a) after running the rreg. You can see it in the example below using the crime dataset. We…
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There are many instances when you may want to take a random sample of your dataset.  For example, you may have a very large data set, and you are trying…
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When going through data management steps in Stata, there are several documentation features available that allow you to attach information to the dataset.  This approach to documenting allows you to…
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Below is the diagram of a simple structural equation model. The dependent variable is a latent variable Acad with three observed indicators, math, science and socst. There are two additional…
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Stata does not have a built-in command to do tests of simple main effects, however ATS has developed a program that will perform them. You can you can the sme…
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For a 2-level hierarchical model, HLM requires two files for a 2-level model, one for level-1 and one for level-2. Similarly, for a 3-level hierarchical model, HLM requires three data…
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This Stata FAQ shows how to check if a dataset has duplicate observations.  There are two methods available for this task.  The first example will use commands available in base…
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