Using R and RStudio for Data Management, Statistical Analysis, and Graphics, 2nd Edition

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“K23166” — 2015/1/28 — 9:35 — page 167 — #193

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Chapter 11

Special topics

In this chapter, we demonstrate some key programming and statistical techniques that

statisticians may encounter in daily practice.

11.1 Processing by group

One of the most common needs in analytic practice is to replicate analyses for subgroups

within the data. For example, one may need to stratify a linear regression by gender or

repeat a modeling exercise multiple times for each replicate in a simulation experiment. The

basic tools for replication in base R include the by() function and the apply() family of

functions (A.5.2). The syntax for these functions can be complicated, ...