I am about to apply traditional univariate GARCH tools to analyze the volatility of the Bitcoin - US Dollar exchange rate.
The index that I would like to investigate is the Bitcoin Market Price (BMP) that is reported by the Blockchain.info information provider at this link: https://blockchain.info/en/charts/market-price. The data can be freely downloaded into a CSV file by clicking at the button that appears at the bottom of the page.
The above page's headline states that the BMP is an "average USD market price across major bitcoin exchanges" which, I guess, are those tracked at this link https://blockchain.info/markets.
My question is:
Is there any available detailed information on how the BMP is calculated?
It would be of particular interest to me to know the following:
a) Is the BMP calculated with the exchange rates that are tracked at the second link above?
b) Is the BMP weighed by the four exchanges' respective transaction volumes?
c) Are Bitcoin trades other than those with US Dollar included in the BMP?
d) If so, which (official/unofficial) fiat exchange rates are used to state the BMP in US Dollar terms?
e) How often is the BMP updated during any calendar day?