presentation base rate

The presentation base rate is the base rate or prevalance encountered in the final context of use. It may not be the same as the overall population base rate if there has been any form of triage, self selection, or filtering before the point of use. For example, the presentation base rate of expertise of the callers to IT support desk, may not reflect that for users of the software as whole nor the population as a whole. When some form of model or statistical data is being used it is critical to know whether the sample base rate that was used to derive it has been normalised to refelect the population base rate and how it differs from the presentation base rate.