What are the selection criteria for the tokens that get included in the indices?

I have noticed that the tokens the were included in the last weekly trader TA index were NOT the tokens that currently had the highest TA on the TM ranking - even if you factor in that the daily trading volume needs to be greater than 500k in order to be included.

I observed the same phenomenon with regards to the weekly price predictions index: The tokens included in that one were NOT the tokes with the highest current price prediction within the next 7 day period - even if you factor in daily trading volume >500k.

So I am curious: What other selection criteria are there for coins to be included in the indices?