What is the inner working of the sandbox filter?

In our research we were able to find how this sandbox / aging filter works. First when google finds a site it gives an inception date (the date when google first found the site). From that time it sees the growth pattern of links. If the algorithm sees lot of not-trustworthy links coming into the site (especially if the site is new) it will place the site in hold from ranking for anywhere between 3 to 16 months. Once the site is in sandbox, Google's algorithm sees the growth of link patterns. If it sees a normal growth of both trusted / normal links it will release the site sooner out of sandbox. But if the algorithm sees growth of un-trusted links the site will be delayed from ranking much longer.