One of the fundamental questions with online advertising is…. how much do I need to spend in order to know if this is working? This is an oft debated point between lawyers and advertising sales people eager to lock unsuspecting lawyers into long term and (frequently) unproductive accounts. And, in general, I find that the longer the contract, the less effective the advertising channel.
In other words, how many clients do we need to land in order to have a strong feel for the efficacy of a marketing investment?