Facebook Insights provides Facebook Page owners and Facebook Platform developers with metrics around their content. By understanding and analyzing trends within user growth and demographics, consumption of content, and creation of content, Page owners and Platform developers are better equipped to improve their business with Facebook.
Check out the Facebook Insights for Marketcalls
Insights are only available to pages which are liked by at least 30 people. Insights will start showing up for your page once your page has 30 users who like it.
Insights is a free service for all Facebook Pages and Facebook Platform application and websites. To see metrics on your Facebook Page or Platform application, go to the Insights Dashboard. Only Page administrators, application owners, and domain administrators can view Insights data for the properties they own or administer.