Dr. Nicholas Christakis of the Harvard Medical School and James Fowler of the University of California have published a study which gives insight in the way people decide to quit smoking.

The study states that people tend to quit smoking in groups. If a member of a group decides to give up smoking, the others are likely to follow as well, with the probability of doing this being related to the type of their relation. For examples, spouses are the most likely to influence each other, the chance being of 67 percent. Next in top are friend connections which tend to influence people with a 36 percent chance of success. Siblings are among the last in line: if someone quits, his brother or sister will do the same thing in only 25 percent of the cases.

Coworkers are also supposed to help each other, but only in small companies, where relations between people tend to be stronger. The study also states that the strength of the relation two people have is most important. Two persons living 100 miles away from each other can both quit if they are very good friends.

Another interesting thing the study reveals is that statistically, if two persons that have never seen each other have a common friend, and one of the persons decides to give up smoking, the other one has a chance of up to 30 percent of doing the same thing, even if the common friend continues to smoke.

The study conducted by the two scientists could have a massive impact in finding better ways to help people give up the unhealthy habit. If until now the effort of convincing and helping people quit smoking was centered on the individual, new strategies focused more on group therapy could be implemented, with probably more chances of success.