See it Here
It is basically the data collected from different sources and with this data we come up to a solution or an argument.
example: Let's say you have a cup of stones (500 stones) Now If we collect data from 50 people and ask them to guess the number of stone in your cup, when you will analyse this data(as done in this repo) you will see that the final result obtained will be very close (+-) to the actual number of stone.