Statistical graphics

Also known as frequency table?

A bar chart must not be confused with a histogram: a bar in a bar chart represents the size of categorical values and is separated from the next bar by a space in between.

In order to display many categories, a horizontal bar chart should be used because of the space needed by the labels.

A special case of a bar chart (combined with a line graph) is the pareto chart.

See also bar charts for data visualization

A histogram is a graphical representation of a distribution. The variable is partitioned on the x-axis into contiguous class intervals (bin widths), usually of equal widths.

The number of classes in a histogramm might be determined with Sturgi's rule: use 1 + log2(N), rounded to the nearest integer, classes.

The Rice rule calculates the number of classs as twice the cube root of observations.

The heights of the bars represent the class frequencies.

A histogram must not be confused with bar charts: the histogram is for continuous data while the bar chart is for categorical values.

Therefore, usually, there is no space between the bars in a histogram.

See also Perl module GD::Graph::histogram

A pareto chart combines a bar chart with a line graph.

The bars are ordered in descending order from left to right while the line shows the cumulative sum of the heights of the bars, also from left to right.

The pareto chart is one of the seven basic tools of quality control.

Pie charts are not well suited to graph many categories, rather horizontal bar charts should be used.

See also Data visualization: Scatter plot

graphic