I am reading a data analysis paper on bitcoin, and there is a phrase I do not get:
We use the Bitcoin transaction data set obtained from Stanford Network Analysis Project. All Bitcoin transactions are documented in a public ledger and are in the currency unit called the Bitcoin(BTC). The data set contains all Bitcoin transactions beginning from the network’s creation until April 7th, 2013. For each transaction, there can be multiple sender and receiver addresses. Furthermore, multiple addresses can belong to a single user.
I do not get this last sentence. Yes, surely a user can create multiple private keys. However, how do we know that a user created multiplie private keys if we are not that user?
The dataset given in this paper is very large (6,336,769 users), so they must apply some algorithm to group private keys belonging to each user. What it would be?