When pitching a VC, you need to have at your command the macro stats for the industry, because that is how they compare your problem with another idea that someone else is pitching. Intuitions are not enough to make the comparison, and for the partner to pitch his/her colleagues – there needs to be some market data about the size of the market etc.
The reason entrepreneurs often skip this step is that it can be really hard to gather market sizing data. As far as I can tell, the only person who’s ever calculated the number of academics in the world is me. Collecting that data took a decent amount of time.
Many entrepreneurs who haven’t done this work will bullshit or semi-bullshit when a VC asks a market sizing question, and the VC is very used to this, and is very good at detecting lack of expertness “um, yeah, er, the market size is $9 billion’. A VC sees straight through that because they get exposed to it so much. You need to answer in a really confident way with as much material as possible to overcome any feelings of doubt from the VC.
Note: Accurately figuring out the size of your market isn’t only for VC pitches. It also allows you to calculate the key startup metric, according to Tom Tunguz — share of habit.