Thom <[EMAIL PROTECTED]> wrote in news:[EMAIL PROTECTED]:
> Some of us remember you! I think your point about avergaes is well made. > I'm sometimes amazed at how people struggle with percentages - until I > remind my self that it is a _tricky_ concept. Percentages and other > averages seem to be difficult because the process of arriving at the > answer strips away the context. So a 29% increase could mean x 1.29 or > an increase from 10% to 39%. And even when talking about percentages as proportions, some people seem to forget that the numerator has to be the count of a subset of the denominator. I've seen too many people try to estimate the prevalence of AIDS in <group> by taking the total number of members of <group> who have been diagnosed with AIDS since 1981 and dividing it by an estimate of the number of <group> members in the current population. This gives wild overestimates because it doesn't take into account the fact that a majority of the people who have been diagnosed with AIDS since 1981 are ex-people and hence aren't counted in the denominator. . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
