Article is devoted to improvement of a method of calculation of these various socio-economic indexes of average sizes which are widely used in statistical practice of the analysis: quadratic and cubic, used in non-standard conditions - for a case of determination of average lengths of the parties of squared figures respectively on the plane (rectangle) and in space (parallelepiped). Approbation of the offered method of calculation of average quadratic and average cubic for determination of average lengths of the parties of squared figures respectively on the plane (rectangle) and in space (parallelepiped) on numerical data is carried out. Some problematic issues of application of the generalizing statistics are considered.