All MCQs

Squaring prevents positive and negative deviations from cancelling.
The resulting variance therefore has units equal to the original units squared.

Standard deviation summarizes typical distance from the mean in the original units.
Larger values generally indicate greater variability.

The interquartile range spans the middle 50 percent of observations.
Because it ignores the tails, it is relatively resistant to outliers.

The five-number summary describes the ordered spread and center of a distribution.
It is also the numerical basis of a standard box plot.

The mode is the value with the highest observed frequency.
It can be used for either categorical or numeric data.

The median depends on the ordered middle position rather than every magnitude.
A few extreme values therefore have limited influence on it.

The arithmetic mean is the sum of the values divided by their number.
It uses every observation and is sensitive to extreme values.

Saved code can be rerun, reviewed, and shared.
This is essential for reproducing data cleaning, analysis, and visualization steps.

summary() reports values such as the minimum, quartiles, median, mean, and maximum.
It offers a quick numerical overview of a variable.

sample() draws elements with or without replacement.
It is commonly used for resampling, permutation, and simulation.

A seed initializes the pseudo-random number generator to a known state.
Using the same seed and code reproduces the same sequence.

NA is the standard marker for a missing value in R.
It is distinct from NULL, which generally represents the absence of an object.