Finally, you simply aggregate up to determine total market size. If you can estimate the average price for what you sell, you can apply this to determine that dollar market size. That's all there is ...

Eligible stocks must have at least 10% of total shares publicly available ... stock market because it relies on the market’s collective wisdom to size stock and sector weightings.

The fund holds a sample of stocks that represent the CRSP US Total Market Index ... of the US stock market because it relies on the market’s collective wisdom to size stock and sector weightings.