New research has shown that you’re more likely to quit smoking if people in your social network are also trying to give up the habit at the same time.

Researchers, Nicholas Christakis and James Fowler analysed changes in smoking behaviour from 1971 to 2003 in a large social network of 12,067 densely interconnected people.

The pair previously conducted research into how obesity is contagious in social networks. Their new research found that the closer relationships are likely to have more influence when one person is trying to quit smoking.

Generally, the researchers found, the closer the relationship between contacts, the greater the influence when one person quit smoking. When one spouse quit, for example, the other spouse’s chances of continuing to smoke decreased by 67 percent. Among friends, the effect was 36 percent. Among co-workers in small firms, 34 percent. Among siblings, the effect was 25 percent. Neighbors did not seem to be influenced by one another’s smoking habits.

So what could this mean if you run your own social network, forum or community blog? If you have a clear aim of something you’d like to accomplish, then a combination of shared goals and peer pressure within closely connected groups could help you achieve your goals.

Surprisingly, people quit roughly in tandem, with whole groups becoming nonsmokers. Those who continued to smoke, meanwhile, formed their own “cliques” that, over time, shifted from the center of the social network to the periphery.

If you have a larger site, then setting up smaller sub groups could help build closer relationships between people. For example, if you run an environmental blog or community site then you could focus your energy on actionable and achievable goals, like recycling. In theory, small closely connected groups will result in behavioural changes. Small groups working together on your site could then influence their own family members and house-mates to change their own recycling behaviour.

Of course there have been large-scale anti-smoking campaigns and these may have also contributed to the decline in the number of smokers. The report also indicates that education might also play a factor in reducing the number of smokers. Focusing too much on one particular outcome might also alienate people and force them to form their own sub-groups.

Those who continued to smoke, meanwhile, formed their own “cliques” that, over time, shifted from the center of the social network to the periphery.

Mark Granovetter’s study looked at the strength of weak ties, but what examples can you think of where close networks are more important than networks with lots of weak ties? Leave your opinions below.