1. Estimators

1.1 Physical notion of estimator

For various reasons, the engineer is forced to make do with a fraction of the information he could gather if the technique were more efficient, or if he had more time, more money... He is thus forced to base his decision not on the widest possible examination of the reference population, but solely on the sample at his disposal. Note that such sampling is sometimes unavoidable, for physical reasons (spherical geometric control, control of solid particle flow characteristics in fluidized beds, etc.).