ABSTRACT
In this age of decisions based on data collection libraries will be expected to gather statistics to describe, evaluate and justify their existence. Whether librarians count people, things, or interactions, even when they use questionnaires, they must understand how assumptions and uncontrolled variables contaminate their work and therefore its implications. Over the past hundred years libraries have been transformed in response to users, politicians, pressure groups and now technologies. How will librarians control and evaluate this resource allocation to preserve mission effectiveness?
