Earlier quoted context omitted.
How do you determine a reputable agency though? I worked next desk to people running a small ad agency. Because we shared office (and I found them an intern), I got a very good look at how they're working. What I've seen can be summarized as: people who have zero clue or interest in statistics writing "reports", with "graphs" they don't even understand beyond "pointing up = good", proving positive ROI to customers -…
Have you ever engaged with the large advertizing holding companies? They have teams of HIGHLY acomplished data scientists, boutique vendors for specific niches etc. Even if you don't pay for it there will be some people skilled at statistics looking at reports. If you pay for it, there will be data scientists doing analysis. The large ad firms deliver a very good product but it usually isn't cheap.
The question isn't are the scientists good, the question is if the vendor is honest.