ePubs ranks results by default using a relevance ranking algorithm, described below. Results can be sorted in ascending or descending order Year of publication, Title and First Author. To change the sort order of results use the Order results by menu in the right-hand panel.

The current order and direction is indicated by an up or down arrow symbol to the left of the current order. To change the sort direction, click on the current order again.

Relevance scoring of results is based on a ‘term frequency–inverse document frequency’ (TF-IDF) scoring model. Results are ordered from most to least relevant. The basic scoring factors are:

• Frequency: the more times a search term appears in a document, the higher the score;

• Inverse document frequency: matches on rarer terms count more than matches on common terms;

• Multiple term matches: if there are multiple terms in a query, the more terms that match, the higher the score;

• Field size: matches on a smaller field score higher than matches on a larger field.