The Google sandbox theory is describes as a Dampening Filter or program that is applied to new websites to hold them back from their true Search Engine Position Ranks (SERP's).
For major Keywords it is assumed to reduce the amount of new websites within the SE results and give some consistency to the Search Engine Results. It is speculated that the Sandbox Effect last anywhere for 2 to 6 to 9 months. It is also speculated that the Sandbox Filter is used to reduce Spam websites and short-term link brokering.
From researching with many keywords and client sites, I have noticed that if a search term contains less than 1 million results, the "Sandbox Effect” is not in place. I can optimize sites for irrelevant terms and rank as soon as the site is indexed by Google. Terms that have more than 1 million results do seem to have the "sandbox effect”. However there is no statistical data to prove a "sandbox effect” is actually taking place. Reason being, that terms that have 1 million plus results have websites that are fully optimized and have significant keyword back links, and proper on site SEO.
Regardless if there is a Sandbox Effect or not, every webmaster should work on their On site SEO and Off site Linking Strategy. Keyword Rich Back links from Various C-Block IPs and one way links are the best.
The Sandbox theory can be used in your advantage if you are dampened in major keywords. Utilize the time to create more
When Linking avoid if possible reciprocal Links, avoid links for Bad neighborhoods, and use common sense in your linking process. A high number of links in any given period could send up red flags to the SE's. Work on consistent linking in a timely manner. Don't go hog wild and purchase 1000's of links in a one monthly time span for example.
If you feel your site is being dampened by the SE Sandbox, filter, use the time to work on good links, and also, develop other websites as well. That way you constantly have sites that are "Out of the Sandbox” and can receive their true SERP positions.
Eric is a Business Analyst and Consultant. Co- Owner of http://www.StmaDeveloper.com and Search Engine Optimization Richmond Virginia