Demographics

The depth of the data can be increased by adding information on sex (easy) and age (harder). You should, however, take into account the time cost of adding information. Observation is demanding work. The bigger the library, the more time it takes to do an observation round. If a single person is involved, he or she can only be expected to register about 150-200 persons per hour (which must include a 15-20 minute rest period between rounds). In smaller libraries, with less than fifty simultaneous users, information on sex can easily be added.

In public libraries with less than twenty simultaneous users, one could also add age estimates. We recommend using four broad age categories:

children - for instance up to twelve years of age
teenagers - or youth from about 13 to 19
adults - from twenty to sixty-five
seniors - above 65