The fact is that not only is it almost impossible to estimate how long it might take for the present H5N1 virus to mutate into one easily transmitted between humans, but it's almost impossible as well to estimate the virulence of such a virus. Sample bias, various epidemiological models, and the fact that extremely virulent viruses are less likely to spread -- because they kill a high percentage of their hosts -- all suggest that a mortality rate of more than 50 percent is much, much too high.
This, of course, does not mean complacency is in order. It does mean that everyone -- health professionals, the media and politicians -- should try very hard not to hype risks or minimize them.
Another figure in the news recently has been the number of Iraqis killed in the war. President Bush mentioned last month that in addition to the more than 2,100 American soldiers killed so far in Iraq, that there were approximately 30,000 Iraqis killed. He was likely referring to the approximate figure put out by Iraq Body Count, a group of primarily British researchers who use online Western media reports to compile an extensive list of Iraqi civilians killed. The organization checks the names and associated details of those killed. It necessarily misses all those whose names don't make it into the reports, and it makes no attempt to estimate the number it misses. The group's list contains almost 30,000 names at present.
A study that appeared in the prestigious British medical journal, the Lancet, in October 2004, used statistical sampling techniques to estimate all Iraqis killed because of the war and its myriad direct and indirect effects. The figure researchers came up with at that time -- 15 months ago -- was approximately 100,000 dead, albeit with a large margin of error. The Lancet study used the same techniques that Les F. Roberts, a researcher at Johns Hopkins and lead author of the study, used to investigate mortality caused by the wars in Bosnia, the Congo and Rwanda. Although Roberts' work in those locations was unquestioned and widely cited by many, including British Prime Minister Tony Blair and former Secretary of State Colin Powell, the Lancet estimates on Iraq were unfortunately dismissed or ignored in 2004.
These last 15 months have considerably raised the American death toll, the IBC numbers, and any update that may be in the works for the Lancet's staggering 100,000 figure. In fact, if the Lancet estimates rose at a rate proportional to the IBC's numbers since October 2004 -- from about 17,000 then to about 30,000 -- the updated figure would be approximately 175,000 Iraqis dead since the war began.
Professor of mathematics at Temple University, John Allen Paulos is the author of best-selling books including "Innumeracy" and "A Mathematician Plays the Stock Market." His "Who's Counting?" column on ABCNews.com appears the first weekend of every month.