Postulate 1. All chance systems of causes are not alike in the sense that they enable us to predict the future in terms of the past.

Both pure and applied science have gradually pushed further and further the requirements for accuracy and precision. However, applied science, particularly in the mass production of interchangeable parts, is even more exacting than pure science in certain matters of accuracy and precision.

Rule 1. Original data should be presented in a way that will preserve the evidence in the original data for all the predictions assumed to be useful.

Postulate 2. Constant systems of chance causes do exist in nature.

Postulate 3. Assignable causes of variation may be found and eliminated.