A report on swine flu cases in the USA has just been published today by the prestigious journal PLoS Medicine. The authors conducted a statistical analysis of hospitalisation, intensive care, and fatalities resulting from the new H1N1 (swine) flu. Because those cases turning up in hospitals are only a fraction of the actual cases (these are the most extreme cases) they employed several techniques to estimate the total number of infections and from that to estimate the rates of fatality etc..