Neilsen just released the image above showing where consumers are spending the most time. It breaks down demographics by age, gender, and ethnicity for television, online video, social networks, tablet and smartphones. For the most part, men and women are pretty equal on where they spend their time. 53% of men spend more time on tablets than women, but women spend more time on social networks. Examine it for more detail and see where your target market falls.
One demographic I hear a lot about just from discussions I have with clients and small business owners are the 50+ year old consumers. I wouldn't count them out of the online spectrum. Their participation levels increase every year. Right now, they're more active on social networks, specifically Facebook. This audience is looking for a higher level of customer service and support. They're researching products and services before they make the plunge the plunge to purchase.
So before jumping to any conclusions about where you should spend your online marketing efforts, really analyze your target market. Get as specific as possible so you can create more personalized campaigns.