APA Dictionary of Psychology

a type of histogram in which the horizontal x-axis is slightly elevated and the vertical y-axis depicts the square root of frequencies using bars that “hang” downward from a curve showing the expected normal distribution. A hanging rootogram allows researchers to see how well their observed distribution (e.g., of debt for a group of middle-class families) fits an expected theoretical distribution. If the observed data differ from the expected pattern, the hanging histogram bars will drop below the elevated horizontal axis, thereby indicating places of poor match between the observed and theoretical distributions. Also called suspended rootogram. See rootogram.