Measures for assessing the data freshness in Open Data portals

Many applications and use cases which consume Open Data rely on up-to-date information. However, scarcely any major Open Data portal provides the users with tangible on how current the data sources are. In order to create a freshness metrics that would solve the mentioned issues, we need to i) learn the change history of a data source and ii) apply a heuristic to estimate how up-to-date a data source is. The following paper assesses which information about the change behaviour of a data source in an Open Data portal are available to derive such a change history. In addition, the paper examines and evaluates different freshness estimation heuristics and establishes a freshness metric for Open Data sources.