Performs t-tests for comparing means of two groups or one-sample t-tests.

Generates random numbers from a Weibull distribution.

Generates random numbers from a negative binomial distribution.

Generates random numbers from a logistic distribution.

Generates random numbers from a log-normal distribution.

Generates random numbers from a hypergeometric distribution.

Generates random numbers from a gamma distribution.

Generates random numbers from a Student’s t-distribution.

Generates random numbers from a geometric distribution.

Generates random numbers from a uniform distribution.

Generates random numbers from a normal distribution.

Generates random numbers from a binomial distribution.

Generates random numbers from a Poisson distribution.

Adds straight lines to a plot.

Creates various types of plots for visualizing data.

Creates histograms of a numeric vector.

Computes the covariance matrix for two or more numeric vectors.

Computes the correlation coefficient between two or more vectors.

Construct contingency tables of the counts at each combination of factor levels.

Displays the internal structure of R objects in a concise and readable form.