POL345 Midterm Key Terms

R

A programming language for statistical computing, data manipulation, visualization, and quantitative analysis.

RStudio

An integrated development environment (IDE) for working with R, including its console, script editor, environment, and other tools.

R console

The interactive area in RStudio where users enter commands and receive immediate results.

R script

A saved file containing R commands that can be edited, executed, and reused.

R object

A named value or data structure stored in the R environment, such as a vector or data frame.

R vector

A one-dimensional collection of values in R, commonly created using c().

R data frame

A tabular R data structure with rows representing observations and columns representing variables.

R assignment operator

The symbol <-, used to assign a value or result to a named object in R.

R comment

Text following # on a line of R code, treated as explanatory annotation rather than an executable command.

R mean() function

A built-in R function that calculates the arithmetic mean of a numerical vector.

R median() function

A built-in R function that calculates the median of a numerical vector.

R var() function

A built-in R function that calculates the sample variance of a numerical vector, using n − 1 in the denominator.

R sd() function

A built-in R function that calculates the sample standard deviation of a numerical vector.

R range() function

A built-in R function that returns the minimum and maximum of a numerical vector.

R head() function

A built-in R function that displays the first several elements or rows of an object.

R Markdown

A document format that combines written explanation, executable R code, and analysis output in one reproducible document.

Reproducible analysis

An analysis organized so that its code, data-processing steps, and documentation can be rerun and inspected to reproduce the results. /