List segmentation can occur at most any point, both in aggregating and compiling data records as well as during and after contact established during a campaign.In my early years we did not have the benefit of PC's, so we manually vetted records based on a cursory eyeball decision as to their likihood to produce a profitable result.

@Michael Quarlesinteresting topic can you please elaborate on this pre NOD listwhat vendor is compiling and selling this list?

I'm beginning to compile a mailing list from listsource.com using many of the filters recommended by some of the experts on BP.

Then the compile everything at year end and file taxes.

You can open a free account and compile the data.

@Andrew HerrigI used Jerry Puckett for his expertise, experience and ease of compiling a viable list. 

Believe me, I just checked (and contacted them for confirmation).You have to go direct to the underlying data compilers - the companies that all these other list providers buy their data from.  

Try and team up with 2 or 3 people in your area and compile your money and efforts.  

Just compiled all the info I found online, formed an action plan and executed.

It's just another source to vet info from (only it's from a ton of investors compiled information over all spans of time).