Insights into collections gaps through examination of null result searches in DLESE

We describe the analysis of zero result searches in DLESE, the Digital Library for Earth System Education, with the intent to use the information to discover gaps in the collection. Close examination of null result searches reveals insights into the kinds of information sought by users but which is missing from the collection. Although it is not possible to consistently isolate collection gaps as a cause for null result searches, it is possible to define a set of null result searches that are very likely to have been caused by collections gaps. This information can be used to improve a collection in specific subject areas. We recommend using this method, along with other inputs, for a digital library with a specific collection scope but a broad and mostly unknown user base, and we recognize the need for automating this analysis.