There are also usually trade organizations that will report information. They have an obvious incentive to make the size seem bigger, but if they are big enough organizations investors will also probably use them as a reference.
The other thing is to consider Total Addressable Market (TAM) vs (SAM) Served Addressable Market. Basically, it is the difference between a complete market and the portion you would be able to serve. This is helpful to keep in mind if you are targeting a niche market. The SAM niche may be small, but if there is applicability to the TAM it could be viewed more favorably.
The other thing is to consider Total Addressable Market (TAM) vs (SAM) Served Addressable Market. Basically, it is the difference between a complete market and the portion you would be able to serve. This is helpful to keep in mind if you are targeting a niche market. The SAM niche may be small, but if there is applicability to the TAM it could be viewed more favorably.
Here is a good link describing SAM vs. TAM:
http://windowmanager.blogspot.com/2005/05/wth-is-tam-sam-som...