Benjamin Disraeli coined the phrase “Lies, damn lies, and statistics,’’ and the phrase (as well as the sentiment) has last- ed—though I like “Truths, half-truths, and statistics’’ bet- ter. In any case, even relatively simple applications of statis- tics can cause problems, not to mention the horrors associ- ated with things like the often misinterpreted SPSS com- puter software (Statistical Programs for the Social Sciences).Probability and statistics, like geometry and mathemat- ics in general, come in two flavors: pure and applied. Pure probability theory is a formal calculus whose primitive terms are uninterpreted and whose axioms are neither true nor false. These axioms originally arise from and are made meaningful by real-life interpretations of terms like “prob- ability,’’ “event,’’ and “random sample.’’ The problem with applying probability and statistics is often not in the formal mathematical manipulations themselves, but in the appro- priateness of the application, the validity of the interpreta- tion, and indeed the “reasonableness’’ of the whole enter- prise. This latter activity goes beyond mathematics into the sometimes murky realm of common sense and the philoso- phy of science (grue-bleen, ravens, etc.). Even though 1 plus 1 equals 2, one glass of water plus one glass of popcorn does not equal two glasses of mixture. The mathematics is fine, the application is not.Babe Ruth and Lou Gehrig played baseball for the New York Yankees. Suppose Ruth had a higher batting average than Gehrig for the first half of the season. Suppose further that during the second half of the season Ruth continued to hit for a higher batting average than Gehrig. Is it neverthe- less possible for Gehrig’s batting average for the entire sea- son to be higher than Ruth’s batting average for the entire season? The fact that I’ve used up a paragraph asking the question indicates that the answer is yes, but how can it be?One way it can be is for Ruth during the first half of the season to hit for an average of .344, getting 55 hits in 160 times at bat; while Gehrig during this same time hits for an average of .342, getting 82 hits for 240 times at bat. During the second half of the season Ruth’s average is .250, since he gets 60 hits in 240 times at bat; whereas Gehrig’s is