As someone who has built TAM models for various industries - I can attest this isn;t always easy. Many analyst firms (former analyst here) typically do some surveys and research among public company revenue reports for the year and then do some pixie dust extrapolating.
The hard thing about a market where startups like Datameer play is that it is a) a nascent market and b) not a "zero sum" game. This makes it difficult to a) fully understand WHICH companies actually are in the market for this flavor of BI and b) know how the space is developing in terms of white space AND disrupting the entrenched BI giants.
You might want to look at the press published versions (read: free) of analyst market share reports, and extrapolate from their. Also, back-channel gossip may give you some revenue numbers on these players - and if you assume pipeline is 3-4x revenue, build a model from there.
Hope this helps.
This is a very good question. Estimating your total addressable market for a big data product like Datameer is both art and science. I've done this sort of analytics for many industries, include technology platforms.
What I do for market sizing questions is to triangulate multiple sources. Remember, using Google is not cheating! If you Google "big data market size", you'll find some resources such as a recent Forbes article. If you dig deeper, you'll want to get your hands on analyst reports from Wall Street firms ( Goldman Sachs, Morgan Stanley, etc.) and IDC. (I've worked for 2 of those 3.)
Total addressable market is a nice number to have. Assuming you can't do everything at once, the harder question to answer strategically for yourself and your investors (if you have any) is "what's my addressable market right now?"
If you'd like some more guidance and specific techniques and pointers, I'd be happy to have a quick call with you. Simply click that Request a Call button.
Best of luck.