Some observations have suggested that two important factors causing this filter are the active age of a domain and the competitiveness of the keywords used in links.
However, as the sandbox effect almost certainly refers to a set of filters in play for anti-spam purposes, it is unlikely Google would ever provide details on the matter.
However, in one instance, Google's John Mueller[6] did mention that "it can take a bit of time for search engines to catch up with your content, and to learn to treat it appropriately.
Google has encouraged companies to reform their bad practices and as a result, demand that efforts be taken to remove manipulative links.
The Disavow tool was launched mainly in response to many reports of negative SEO, where companies were being targeted with manipulative links by competitors knowing full well that they would be penalized.
At the same time, some anecdotal case studies have been presented,[11] which suggest that the tool is effective and that former ranking positions can be restored.
A "reverse sandbox" effect is also claimed to exist, whereby new pages with good content, but without inbound links, are temporarily increased in rank — much like the "New Releases" in a book store are displayed more prominently — to encourage the organic building of the World Wide Web.
He asserts that "no one knows for sure if the Google sandbox exists", and comments that it "seems to fit the observations and experiments of many search engine optimizers".
[4] In an interview with the Search Engine Roundtable website, Matt Cutts is reported to have said that some things in the algorithm may be perceived as a sandbox that does not apply to all industries.
[26] Jaimie Sirovich and Cristian Darie, authors of Professional Search Engine Optimization with PHP, state that they believe that, while Google does not actually have an explicit "sandbox", the effect itself (however caused) is real.