Describing Location in a Distribution

Percentile

Percentile

the pth percentile of a distribution is the value with p% of observations less than or equal to it

Cumulative relative frequency graph

plots a point corresponding to the percentile of a given value in a distribution of quantitative data. Consecutive points are then conected with a line segment to form a graph

Standardized score (Z-score)

for an individual value in a distribution tells us how many standard deviations from the mean the value falls, and in what direction; calculated using z=value-mean/standard deviation

Transform data

occurs when changing units of measurements