Yes, I ask often. And I track it in Quickbooks, using the "class" list. You select which class the customer belongs to right when you are generating their invoice.
I have classes for everything........yard signs, yellow pages, referrals, contractor referrals, "saw us working", and one called "existing customer" used for repeat business.
I ask everyone we give a bid to but I haven't been able to keep a good record of the responses yet. I'll be doing a computer upgrade sometime this month and hopefully then I will be able to track things much better. But for the short term, I've been able to realize that the yellow pages have been 90% of my jobs except for cold calling.
Mark,
I ask every caller how they heard about me and keep accurate
track of the source. It helps to determine how to spend ad $'s
in the future. I have asked everyone since day one and keep
the sources year to year. This also helps to solidify referrals
as I send them a gift certificate for a referral that turns into a
completed job.