Hello - Sorry if this is a newbie question, but where does the data for public betting percentages come from? Do line services like Dons Best, Sports Insights, etc. all get that data from a single source, or do they each compile that information on their own? Do these percentages include data from all books, or just online books? And why do the books have any incentive to share this data in the first place?
Again, sorry if this is noobish, but I've tried to Google the answer and haven't come across any convincing explanations. Thanks!