Introduction

We have talked previously about the purpose of different elements of resource description. In this chapter, we discuss what makes for effective metadata, as not all metadata fulfils its purpose equally well. There are several aspects to metadata quality, all of which the metadata specialist, in particular, needs to bear in mind. We shall also look at mechanisms for improving the quality of metadata, such as vocabulary control, and for assuring quality, and end our discussion by considering the costs that effective metadata incurs.

We should note first that the quality of metadata is dependent on both the elements represented and the values of these elements. We shall start by revisiting our earlier discussions about how some elements may be more functional than others in addressing users’ information needs. We shall also consider the importance of comprehensiveness, whereby fuller descriptions, with more elements, address users’ needs more thoroughly. Moving on to values, we shall discuss how their accuracy and clarity affect quality, and then spend some time on an aspect of great importance at both element and value levels, namely, consistency.

Functionality

Numerous metadata elements could be recorded in the description of an information resource. Some, however, are likely to be more useful than others. As we have already noted, their utility depends on the information context: users’ needs, users’ behaviour, the retrieval system and so on. Since it is not feasible to include all possible elements in a description, those that are included should be the most supportive of functional requirements. Determining exactly which ones these are is no easy task, and inevitably involves a degree of guesswork (we cannot be sure of future use), but careful study of the information context usually provides the metadata specialist with plenty of pointers.

Some aspects of the information context may be easier to study than others. Metadata specialists should generally be able to ascertain how their retrieval systems work, at least in basic terms. This may cover indexing rules, indicating which elements are indexed for certain searches, and which ones are not. If a particular record element is not indexed, this makes it of no use for the purposes of finding resources. Systems knowledge may also extend to display rules.