That's the thing though; I have only passing familiarity with many of the concepts you listed. In order to evaluate someone on them, I would have to learn enoug

That's the thing though; I have only passing familiarity with many of the concepts you listed. In order to evaluate someone on them, I would have to learn enough to differentiate a real expert from a talented bullshitter, and I'm frankly not confident in my ability to do so in the time I have available. We've tried working with several marketing firms specializing in ppc, and after a couple of failures have found one that's getting decent results. They understand our business and can write reasonable ad copy. And the traffic driven by the ads is at a CPA that works for us, and has meets the KPIs I'm interested in on-site, in terms of conversions, time on site, retention, etc. However, I have no idea whether it's possible to do considerably better than they are. And as I mentioned initially, I feel the amount spent might be better put toward an in-house employee, who could devote greater effort than I assume the agency does, as well as performing non-ppc marketing tasks. But beyond just trying people who seem good until I find one who gets results, I'm not sure how to find that person. Maybe that's exactly what I should do.