Histogram is a compilation of data, in the form of a statistical chart consisting of adjacent bars (rectangles), which illustrates the number of occurrence of test features in population or sample.

The base (which rests on the horizontal axis) are size of class compartments.

This method of construction is used when a number of distribution ranges are equal. If the series has unequal intervals, the height of the rectangles is determined by the index of abundance (frequency) corresponding to the various classes.

Indices of abundance (frequency) shall be determined as follows\[{\text{IofA}} = \frac{k*i}{l}\]


k - abundance of the class,
i - narrowest class interval
l - class interval.

The histograms are used mainly to present the structure of the population (or phenomenon), hence structural series of qualitative and quantitative characteristics.

Charts highlighting the basic features of the population (or phenomenon) must be precisely adapted to the nature of these features.

Histogram Construction

The Histogram as other statistical charts consists of several parts:

  • field,
  • bars,
  • scale,
  • title,
  • legend,
  • source.

The basis for drawing up a histogram that describes the accuracy of the occurring in population (phenomena) is a rectangular coordinate system, with the main attention to the selection of the scale and precise graphical image.

A special form of the histogram is cumulative histogram. The horizontal axis in a rectangular coordinate system the accumulated numbers are shown.