What does "Relevance" mean in ScienceDirect?

Factor

Calculation

Number of hits

The more often a term occurs in a document, the more likely that it is relevant to the topic of the article. So, the number of times a term appears in a document plays a role in calculating relevancy and is described with more detail in the sections below.

How significant is a word?

Not every word is equally important. A term that occurs in nearly all documents will score less than something unusual. We use calculations based on Term Frequency/Inverse. ScienceDirect uses Document Frequency (TF/IDF) (a concept originally introduced by Karen Spärck Jones, 1972*) to assign a weight to any particular word in any collection of documents - in this case all the documents in ScienceDirect.

For example: The word "experiment" is likely to be found quite commonly in all subject areas in ScienceDirect, whereas a word like "crocodile" or "Cryptococcus" is less common across the whole range of subjects and will have more impact on ranking.

Where is the word found?

It is also important where terms occur in the document. If a word is in the title, abstract, or keywords in a scientific article, then it is probably very important. If it is only mentioned in the references, it probably is not very important. To reflect this contrast, ScienceDirect assigns different weights to hits in different sections of the document.

Position in the document

The earlier in the text a term occurs, the more important it is likely to be. The position of the first occurrence therefore contributes to the ranking.

Proximity

The closer together different terms from the query are found, the higher the score.

Completeness

If a query consists of several words, then a document that contains all the words within the same field will score higher than one in which the words are scattered throughout the document.