Query Deserves Freshness (QDF), is a Google re-ranking function. It essentially means: Search requests that deserve up-do-date search results. It can drastically change the appearance of a search result and can occur for search terms that change their meaning over time.
By using QDF Google is trying to identify the topics and search requests where the user has a desire for new and current content, to position up-to-date information on these search results.
QDF (Query Deserves Freshness) – a mathematical model that tries to determine when users want new information and when they don’t.– Definition
The QDF algorithm was invented by Amit Singhal, Senior VP and Google Fellow, who first talked about it in 2007. QDF has been a ranking factor ever since.
How does the Query Deserves Freshness algorithm work?
QDF always comes into play when a topic sees a sudden rise in relevancy/mentions (news reports) and traffic (search volume).
To do this, Google monitores 3 sources:
- Blogs and magazines
- News portals
- Search requests
If all 3 sources cover a specific topic and the mentions and search requests of said topic are higher than average as well as current, the Query Deserves Freshness algorithm ranks new content for this topic, by authorities in the field, higher on the search results. This, however, only lasts for the duration of the “public interest” in this topic.
The QDF solution revolves around determining whether a topic is “hot”. If news sites or blog posts are actively writing about a topic, the model figures that it is one for which users are more likely to want current information. The model also examines Google’s own stream of billions of search queries.– Amit Singhal, Senior VP und Google Fellow
Example: QDF in the real world
Anytime a new product by a well known brand is revealed, for example when the new version of the Mercedes A class came out in 2012, and there is enough public interest, then new and subject-relevant content will get a ranking boost thanks to QDF.
It is quite possible that the Query Deserves Freshness algorithm was responsible for new content, which was high quality and relevant to the subject, to show up in the search results for [mercedes a klasse] in September of 2012.
In this case, Google would have flagged the search request [mercedes a klasse] with a QDF-Flag, seeing how all three sources above showed interest in this subject.
Video Answer by Google/Matt Cutts on QDF
Additional information about this topic:
- Google Keeps Tweaking Its Search Engine – Interview with Amit Singhal in the New York Times