Data revision of the day — good news this time

The United Nations’ top AIDS scientists plan to acknowledge this week that they have long
overestimated both the size and the course of the epidemic, which they
now believe has been slowing for nearly a decade, according to U.N.
documents prepared for the announcement…the latest estimates, due to be released publicly Tuesday, put the
number of annual new HIV infections at 2.5 million, a cut of more than
40 percent from last year’s estimate, documents show. The worldwide
total of people infected with HIV — estimated a year ago at nearly 40
million and rising — now will be reported as 33 million.

Here is the full story, which also explains the sampling errors behind the earlier estimates.