How do cryptocurrency analysts calculate market size?

Could you elaborate on the methodology cryptocurrency analysts employ to calculate the market size of digital currencies? Do they primarily rely on transaction volumes, market capitalization, or a combination of both? Are there any additional metrics or factors that analysts consider in their assessments? Furthermore, how do these calculations differ across various cryptocurrencies, and how do they account for the volatile nature of the digital currency market? Understanding the nuances of these calculations would greatly assist in evaluating the overall health and potential of a cryptocurrency.