This is another takeaway phone sourcing lesson from that prodigious and infamous RBC string about sourcing being dead:

Keith, you asked:
A question: approximately how many calls do you need to make to actually speak to 100 identified potential candidates, or conversely, how many identified potential candidates will you be able to speak to the first time out of 100 calls made with proper information?

Good questions. On the first one (approximately how many calls do you need to make to actually speak to 100 identified potential candidates) I'm not sure if you're asking me how many calls does a phone sourcer need to make to ID 100 potential candidates or how many calls does the recruiter need to make to reach the 100 identified potential candidates that the sourcer IDed (sounds like a Peter Picked Pickles, doesn't it?) Please clarify.

On your second question (how many identified potential candidates will you be able to speak to the first time out of 100 calls made with proper information) the key word in your query is "first". If you have 100 potential candidate names in front of you with the proper and correct information* when you sit down on a Tuesday, Wednesday or Thursday (notice I don't recommend Monday or Friday calling) morning whose titles/job skills fit the open position you need to fill, you will reach, on your first call-through of the list, maybe 10-15 of those listed actually answering their phones. On your second list-call through, again, maybe 10-12. On your third and fourth call-throughs, maybe 8-12. And it drops from there. A list of 100 may need to be "called through" a dozen times before you actually reach everyone or near everyone. This is a factor of the society we live in -8 out of 10 business calls these days go into VoiceMail! But remember, each time you do a call-through, the number of people you have yet to reach declines. A list of 100 usually takes a dedicated/successful recruiter a couple weeks to thoroughly exhaust.

The word "exhaust" above is a misnomer here - that list of 100 - especially for those who specialize in a specific area - becomes ever more valuable as time goes on. That list of 100, besides more than probably providing a hire or two out of the first set of rounds of calling, is only the beginning of a recruiter's opportunity to get to know and develop relationships with people that will (naturally) turn into additional future hires. I have a saying that it's really the only product I know of that creates increasing returns (instead of decreasing returns ordinarily found in economic theory) over time!

I hope I haven't confused things.

*proper and correct information = name, title, phone number (preferably a direct dial)
Remember, the recruiting's up to you!
The first part of this lesson on metrics can be found here.