Insider information about Google's ranking algorithm

The New York Times has recently published an article about Amit Singhal.

Amit Singhal is in charge of Google's ranking algorithm. The interview reveals some interesting facts about Google's ranking algorithm.

Google knows that its algorithm is not perfect

"Tweaking and quality control involve a balancing act. 'You make a change, and it affects some queries positively and others negatively,” [...] 'You can’t only launch things that are 100 percent positive.'"

"[...] Any of Google’s 10,000 employees can use its 'Buganizer' system to report a search problem, and about 100 times a day they do."