Bias of the Sample

One issue that arises with sampling is the bias of the sample. When data are selected for
inclusion in the sampling database, there is ALWAYS a bias of the data. What the bias is
and how badly the bias colors the final analytic results are a function of the selection
process. In some cases, there is a bias, but the bias of the data really doesn’t matter. In
other cases, there is a real impact made on the final results because of the bias of the data
selected for the sampling database.

The analyst must constantly be aware of the existence of and the influence of the bias of
the sampling data.

Fig. 9.1.12 shows that there is an expensive marginal value of accuracy when processing
sampling data.

Chapter 9.1: Repetitive Analytics: Some Basics