25. Difficulty of discussing by our rules cases in which arbitrary interference can be postulated.
26, 27. Consequent inappropriateness of many arguments.
[CHAPTER XVIII.]
ON THE NATURE AND USE OF AN AVERAGE, AND ON THE DIFFERENT KINDS OF AVERAGE.
§:nbsp;1. Preliminary rude notion of an average,
2. More precise quantitative notion, yielding
(1) the Arithmetical Average,
3. (2) the Geometrical.
4. In asymmetrical curves of error the arithmetic average must be distinguished from,
5. (3) the Maximum Ordinate average,