Who is really on Facebook?

The statistics on who uses Facebook are very valuable to companies.  Specific demographics are what makes Facebook's advertising so great; as companies can target the exact audience that they need.  I find it really interesting to note that 70% of Facebook users are outside of the U.S.  I would have assumed a higher percentage of U.S. users however this statistic is a great thing for Facebook and international advertisers.  This is enhanced moreso by the fact that 40% of users follow a brand on Facebook and 51% of those followers will purchase a product from that specific brand.  

Now, let's contrast that with Twitter.  Twitter has less than 1/5 of the number of users as Facebook however 52% of Twitter users update their statuses everyday as opposed to 12% for Facebook users.  This leads me to believe that Twitter users are more active than Facebook users and may be more likely to buy products.  The statistics show that 25% of Twitter users follow a brand and 67% of brand followers buy a product.  

From a company's perspective, this may sway the company from advertising with Twitter rather than Facebook.  There may be a better bang for the buck advertising with Twitter than Facebook.  These are all things that companies must cnosider in their cost benefit analysis in social network advertising.