The raw data is a list of the exact values for each tested area of your chromosomes, made available in a spreadsheet format. When you have the raw data you can do several things:
You can send it to Dr. Doug McDonald at the University of Illinois. He has his own data base and program to do admixture (deep ethnicity) analysis, which you can then compare with your Ancestry.com findings.
You can upload your data to Gedmatch.com. There you can find other admixture tools (Dodecad, Eurogenes, Harappa, etc.) which can give you other insights about your ethnic origins.
On Gedmatch you can compare your autosomal and XDNA to others who have uploaded their data, regardless of which company the tested with.
A chromosome comparison tool lets you see graphically or in tabular form which specific segments you share with your match. You can combine that with an "in common with" tool to identify any other matches who share those segments. That can help to identify several individuals with whom you might share a common ancestor and facilitate solving the mysteries.
In my own case, I have my raw data from FTDNA. I sent it to Dr, McDonald and used all of the Gedmatch admixture tools. That gave me more information about my ethnic origins than Ancestry did.
I also found new cousin matches through Gedmatch to people who tested with both FTDNA and 23and me.
Using the comparison tool I found that I share an identical segment with a person whose family lived near mine in Ireland and a woman from Australia who had a brick wall with an ancestor in London. We are still investigating, but it looks like her orphaned GGF had an ancestor from Cork, which is helping her to narrow the search.
Another valuable tool that is available elsewhere is the ability to search your matches for a common surname. I have a lot of Morgan matches and would like to be able to compile a list of all of them to look for patterns that might help me identify where they fit into my tree.
Hope this helps.