Deep Web is just one method amongst many in the means and methods of information gathering.  But you have to milk that information for useful trends or  intel via analysis.

Researchers specifically Intelligence Analysts, need to make sense of the results of their findings. For those who are new to the craft of intelligence and analysis, I’ve attached two documents from the US government that may be helpful

Intelligence Analyst toolbox – a basic overview of the tools you will need in intelligence. About a dozen pages Intelligence_analyst_toolbox

intelligence as an investigative function – a primer on intelligence analysis and the basics.

Computer augmented intelligence analysis – a overview on some algorithmic methods to aid analysis

Baysian analysis for intelligence – Using Baysian analysis. A Declassified document from the CIA.

It is also good to understand the intelligence cycle. Here in a short video is a rough overview of the intel cycle. While focused on IMINT, it applies to SIGINT, GEOINT, TECHINT, HUMINT, etc…