A classical measure of location, equal to the inverse of the arithmetic mean from the reciprocals of the individual values of the examined feature. It is used to determine the mean value where the characteristic values are expressed in terms of the constant unit of another variable, that is, in the form of intensity indicators, e.g. vehicle speed in km/h, work efficiency in pcs/h, etc.

• Structural point series
• Series of distribution with class intervals
• Detailed series