It's a pretty technical read, but this recent Microsoft report, "Sex, Lies and Cyber-crime Surveys" by Dinei Florencio and Cormac Herley tries to support an interesting hypothesis:  cyber-crime surveys that suggest huge losses from hacking and phishing aren't reliable.  Here's an excerpt of their thinking:

First, [cyber-crime] losses are extremely concentrated, so that representative sampling of the population does not give representative sampling of the losses. Second, losses are based on unverifed self-reported numbers. Not only is it possible for a single outlier to distort the result, we find evidence that most surveys are dominated by a minority of responses in the upper tail (i.e., a majority of the estimate is coming from as few as one or two responses). Finally, the fact that losses are confined to a small segment of the population magnifies the dificulties of refusal rate and small sample sizes. Far from being broadly-based estimates of losses across the population, the cyber-crime estimates that we have appear to be largely the answers of a handful of people extrapolated to the whole population. A single individual who claims $50,000 losses, in an N = 1000 person survey, is all it takes to generate a $10 billion loss over the population. One unverified claim of $7,500 in phishing losses translates into $1.5 billion.