Source: http://www.thesempost.com/how-google-uses-clicks-in-search-results-according-to-google/
During SMX Advanced event, webmaster trend analyst Garry Illyes mentioned that clicks does not affect ranking positions. Click data gathered is used on experimentation and evaluation purposes.
Importance Of Click Through Rates
Noisy Clicks
It can’t be denied that click through rate can be easily manipulated and would result to noisy clicks which can clutter search results suppose it will be used as a ranking factor. Google can recognize clicks coming from bots or clicks with intention to increase click through with their latest algorithm updates.
Personalization
Search result prediction plays a big role when Google is serving search results to a user. Take for example, a user types “mouse” to look for a computer peripheral. The first result would include an animal which is not related to what the user is looking for. Once you search again adding more keywords to be specific, Google will show you suggestion that is close to what you are looking for.