More information about reporting results of statistical tests . The following example shows how different bar fill patterns have been used to distinguish three species of fish. Frequency histograms are bar-type graphs that show the frequency of occurrence of data values for a sample variable. Frequency can be absolute , i.e., number of counts , or relative, i.e., percent or proportion of the sample. A common example would be a histogram of exam scores showing the number of students who achieved each possible score.
Frequency histograms are also important in describing populations, e.g., size and age distributions.
Examples would include chart records from physiological studies, electrophoresis results, autoradiographs, photographs, etc. These data are presented as Figures and have an appropriate legend.