I do not know how they go about coming up with the figures and exactly what they mean, but one has to seriously consider the following scenario. Anyone can correct me if they have any other ideas.
70% correspondence rate with EEG for microsleep in 15 second interval means that there is 30% chance of microsleep escaping detection with CRAM (assuming EEG was accurate--which, again, is not necessarily true). That means that for every microsleep that avoided the detection during the first 15 seconds it would have another 30% chance of avoiding detection during the next 15 seconds for the total and simplified probabilty of 9% (0.3 x 0.3 = 0.09). In other words, CRAM has 90+ percent probability of detecting microsleep in 30 seconds.