Google says on its new “How Search Works” site that it launched 665 “improvements to search” in 2012.

In a graphic looking at data from 2012, Google explains that it had 118,812 “precision evaluations,” which are described as “The first phase is to get feedback from evaluators, people who evaluate search quality based on our guidelines. We show evaluators search results and ask them to rate the usefulness of the results for a given search.”

From there, it had 10,391 side-by-side experiments.

“In a side-by-side experiment, we show evaluators two different sets of search results: one from the old algorithm and one from the new, and we ask them for details about which results they prefer,” Google explains.

You can see Google’s Search Quality Raters Guidelines (at least a “cliffs notes version“) here (pdf).

Google ran 7,018 live traffic experiments in 2012. “If the evaluators’ feedback looks good, we move forward with a ‘live traffic experiment,'” Google explains. “In these experiments, we change search for a small percentage of real Google users and see how it changes the way they interact with the results. We carefully analyze the results to understand whether the change is an improvement to the search results. For example, do searchers click the new first result more often? If so, that’s generally a good sign.”

From there, came the 665 actual launches.

“Finally, our most experienced search engineers carefully review the data from all the different experiments and decide if the change is approved to launch,” says Google. “It sounds like a lot, but the process is well refined, so an engineer can go from idea to live on Google for a percentage of users in 24 hours. Based on all of this experimentation, evaluation and analysis, we launched 665 improvements to search in 2012.”

Typically, Google has been providing monthly lists of “search quality highlights” showing some of the tweaks they’ve made, but they haven’t done it in months. Despite today’s effort in transparency, it remains to be seen whether we’ll see exactly what Google has been up to since October.