Women keep their personal lives and business lives very separate when it comes to social media, according to the 2009 Women in Social Media Study by BlogHer, iVillage, and Compass Partners. While women consider blogs great sources of information, especially regarding purchases, the vast majority of women use social networks solely for keeping in touch with family and friends.

Over half (55%) of the women surveyed in said they participate in some kind of blog activity (publishing, posting comments, reading), and 53% use social networks.

But here’s the kicker : Women use social networks in the purest sense only; 75% use them to keep in touch with friends and family, and not so much as information sources or for making purchase decisions. That’s a major insight considering this is the half of population making 85% of purchase decisions in the US.

In contrast, women rely more on blogs for the business of life, and are twice as likely to use blogs than social networks as an information source (64%), for advice and recommendations (43%), and opinion sharing (55%). Women are 50% more likely to use social networks merely as a means of keeping in touch.

A third of those participating in social networks are loyal to just one and do no other social media activities on a weekly basis. There are likely infinite reasons for that, but it sheds a rather harsh light on why only 20% of women appear to use Twitter.

It could mean that most want all of the networking under one roof for convenience, and only desire one-to-many communication if it involves people they know and trust. It could also mean that Twittering is still considered a medium for celebrities, politicians, and digital hipsters; the survey found that women who themselves blog are significantly more active across all forms of social media.

“Bloggers have a broad reach in the social media population and the survey demonstrates that women who blog are the most actively engaged social media participants — constantly seeking out new ideas and ways to share their opinions about those ideas,” said Susan Wright, president of Compass Partners.

And other women are listening, perhaps more than they are to traditional media. Thirty percent are watching less TV, 31% are listening to less radio, 36% are reading fewer magazines, and 39% are reading the newspaper less.

Numbers like that indicate a huge shift in the media landscape: the sex making the most purchase decisions are rejecting traditional media in favor of online sources. Forty-five percent of women in the survey said they decided to purchase an item after reading about it on a blog; among the women in the more digitally savvy BlogHer network, that number is 85%.

Women bloggers are twice as likely to share a positive purchase experience on blogs and/or message boards and about 40% more likely to share a negative experience. So it’s a good idea to be very, very nice to women bloggers, especially since they are likely to carry significant influence with non-blogging women.

“At a time when the economy is top of mind for more than 70 percent of these active social media participants, women who blog are turning to online resources, including blogs, to help them make their day to day purchasing decisions,” said BlogHer cofounder Elisa Camahort.

The results of the survey are concluded according the answers of 2,821 women in the general US population, 1,008 women in the BlogHer network, and 788 women in the iVillage network.

About the Author : Jason Lee Miller is a WebProNews editor and writer covering business and technology.