Digital market research company eMarketer has said that the online world, and in particular, social media significantly affects offline buying behaviour of consumers.

A survey by Knowledge Networks and MediaPost Communications found that, in May 2011, 40% of respondents accessed social media via their mobile phones, an increase from 28% who reported doing the same in September 2010.

The survey included teen and adult social media users for "The Faces of Social Media" study. It found that 37% of US social media users trust what their friends and family members say about a brand or product on social media.

People also listen to what strangers are saying about a product, but it is less at 10%.

Blogposts by friends and family members also impact the consumer behaviour, with 26% trusting what friends and family members say in blog posts. One-in-four trust their posts on social media sites and 20% trust their tweets. This is compared to 7% who trust the blogs and posts of strangers, and 5% who trust strangers’ tweets.

The study also found that 27% of US mobile Internet users turned to social media to compare or check prices before, during or after shopping.

Nearly 25% checked reviews and 16% got coupons or discounts for local businesses.

Overall, the study found, half of mobile Web users interacted with social media at some point in the shopping process.

Another study conducted in April 2011 by ROI Research found that 60% of US social network users were at least somewhat likely to take action when a friend posted something about a product, service, company or brand on a social media site.