[Kisil]

And did you find out how many of the up and neutral clients also came from the yellow pages? That bit of information is useful only if it draws a distinction, e.g. what if the agency only had one working form of advertising?

(Of course this almost goes without saying, and I don't doubt you thought of it, but this is such a common logic error that I thought it shouldn't be left hanging in a public forum.)

[JacobAldridge]

Yeah, sorry I didn't want to make my response longer than needed to be.

None of the Up or Neutral clients were Yellow Pages - most were referrals from the same level (ie, Up / great clients had been referred mostly by other Up clients, and similarly with Neutrals, plus some general networking). Which does reinforce the 'you are who you hang with' conclusion I've drawn.