I've hugely enjoyed Malcolm Gladwell's books in the past (Tipping point, Blink, What the dog saw...) they make important points with an elegant simplicity. In a similar vein, his point below is reasonably simple: that “more data increases our confidence, not our accuracy,”.
It's a point well made. In online B2B marketing, we have access to large amounts of data with astonishing granularity. However, at a human level, this access is very recent and we cannot have established when to analyse and when to ignore data. The tendency is to continue mining and testing and learning but Malcolm suggests (and I agree) that sometimes that can lead to missing the wood for the trees. That when your head is down looking at the data, you're not taking a broad view of what your client really wants.
This can lead to excellent tactics within a broken strategy.