Chief Marketing Officer Bill Muller elaborates: "Specifically, when performance is aggregated across all the brands that include email as one of many channels clients run through Visual IQ’s TrueAttribution process to create algorithmically-attributed TrueMetrics, the CPA on 54.2% of their spend is off by at least 40%."
Additionally, the CPA on more than 10% of that spend is off by at least 500%. Costs factored into Visual IQ's model for email include list rental, fees paid to email service providers, and creative production.
That might seem a striking disparity, but it compares favorably to the display ad channel, where Visual IQ's 2012 data suggests 94% of spend goes to placements with a "CPA skew" that is 70%+ lower than "last click" metrics. (AdExchanger story)
It should be noted that Visual IQ's data does not indicate whether brands are using "last click" metrics – only whether those metrics are over- or under-valued.