APA Dictionary of Psychology

a formula that gives the probability, from 0 to 1, that a variable will have a score less than or equal to a specific value. When this is plotted on a graph, the vertical y-axis will indicate the probability value from 0 to 1 for each possible score of the variable listed along the horizontal x-axis. This type of graph usually shows a pattern with a curve that rises from the lower left up to a peak at the upper right, where for the last score the probability that a variable will have a value equal to or less than the highest possible score is 1. Also called distribution function.