Fundamentals of Statistics contains material of various lectures and courses of H. Lohninger on statistics, data analysis and here for more.

Frequency Polygons

Frequency polygons are basically the same as histograms where the rules valid for histograms are also valid for frequency polygons. They are a smoother alternative to histograms. Frequency polygons can be constructed from histograms by joining the midpoints of the histogram bars with lines. The areas below the histogram and the frequency polygon are equal. In general, one should prefer to use histograms rather than frequency polygons, as the width of the classes cannot be seen well in frequency polygons. Frequency polygons should be used for data on a metric measurement level only. For the bin width the same rules apply as for the histograms.

Hint: Do not mix up frequency polygons with the cumulative frequency distribution.

Last Update: 2012-10-08