Distributions, Variation, and Percentiles

Vocabulary flashcards covering key terms from the lecture notes on distributions, variation measures, and percentile calculation.

Frequency distribution

A distribution that shows how often each value or class occurs; can be symmetric, uniform, or skewed.

Symmetric distribution

A distribution that can be divided by a vertical line into two mirror-image halves.

Uniform (rectangular) distribution

A distribution in which all entries or classes occur with equal frequency; also symmetric.

Skewed distribution

A distribution whose tail extends more to one side than the other.

Skewed left (negatively skewed)

A distribution whose tail extends to the left.

Skewed right (positively skewed)

A distribution whose tail extends to the right.

Dispersion

The spread or variability of a set of observations.

Range

The difference between the maximum and minimum data entries.

Coefficient of variation

A measure of relative variability defined as standard deviation divided by the mean, expressed as a percentage.

Standard deviation

A measure of dispersion; the square root of the average squared deviations from the mean.

Mean

The arithmetic average of a data set.

Percentile

A value below which a given percentage of observations fall; the p-th percentile divides the data so that p% lie at or below it.

Rank

The position used to determine a percentile; in this procedure, rank = p(n+1).

Interpolation

Estimating a value between two observations when the percentile rank is not an integer.

Interpolated percentile value

The percentile value obtained by interpolating between the two closest observations based on the fractional rank.