Harmonic mean is a central value of a data set which can be computed using arithmetical operations. It is generally used in averaging rates, ratios etc. It is well defined and suitable for algebraic treatment. It takes all the observations into account. In the case of outliers even though it mitigates the effect of very large values, but affected by very small values. Harmonic mean is the smallest when compared to the Arithmetic and Geometric Means.

Harmonic Mean can be defined as the ratio of the number of elements in the data set to the sum of the reciprocals of each value in the set. Harmonic mean is used to calculate the average of a set of numbers. It can be calculated by dividing the number of observations by the reciprocal of each number in the series.