When I was a wee little lad I use to think economics was supply and demand, you understand these two principles and you have it made. And it got me through high school economics and even a very rigorous college course. The older I get; however, I see that economics is more people acting upon incentive and de-centive. The only reason supply and demand exist is because someone wants something and are willing to do or pay a certain amount for it.
What does this have to do with board game design? Well I have just played 2 games I made for the first time with large amounts of people and the games went better than I had planned because the players did and acted exactly the way I wanted them too and the reason they acted the way I wanted wasn't because I told them how I envisioned the game necessarily or because I had rules telling them how to act at all times but rather because I put incentives in the game for the player to act the way I wanted them too.
I had a dungeon crawl game in which I didn't want the players sticking together at all times, so I put a simple rule that gave a large reward to the player who was the first to discover and enter a new room. Everyone wanted the best for themselves and naturally split apart and without me saying anything; they did precisely what I wanted.
I was literally so pleased with the results of the two games that I had to just share how I did it in hopes that others might benefit from economics. Most of us already do this, but it was worth mentioning.