Basic Statistical Functions in R
Instruction: Explain how to use the 'summary' function in R and provide an example using any dataset of your choice. Describe what statistical information the function returns by default.
Context: This question evaluates the candidate's familiarity with R's built-in functions for descriptive statistics. It checks the candidate's ability to leverage R's capabilities to summarize key statistical information about data, which is crucial for any data analysis task.
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summary is a generic function: its output depends on the object's class. Numeric vectors usually report minimum, quartiles, median, mean and maximum, plus a missing count when present; factor methods count levels. A model summary is model-specific.
x <- c(1, 2, 3, 4, NA_real_) s <- summary(x) stopifnot(unname(s["Mean"]) == 2.5, unname(s["NA's"]) == 1) group...