Searching cultural heritage data: Does structure help expert searchers?

On-line search requests of cultural heritage (CH) material are often very short and mainly focused on names and dates, while the data provides much more detail and is highly structured, based on classification systems and ontologies. Apparently, typical users make no use of the available information and structure. Expert users such as museum curators have extensive knowledge of the objects in the collection and the classification systems used to describe them, and have complex information needs. In this paper we investigate the impact of exploiting the metadata structure on retrieval effectiveness of complex queries. Our findings are that 1) expert queries require little smoothing as all terms are important for identifying the right objects, 2) the field structure of CH descriptions can help improve early precision, 3) combining free-text retrieval and structured Boolean retrieval leads to significant improvements on both approaches alone. Finally, from analysing the questions send to a museum, we find that non-experts have more complex information needs than what search logs show us, suggesting they can benefit from systems that exploit structure as well.