[EMAIL PROTECTED] (Robert J. MacG. Dawson) wrote in news:[EMAIL PROTECTED]:
>> > My experience has been that if I encounter any argument that >> > asserts that there is no such thing as bisexuality in human males, >> > I will not have to read very far before the author defines a >> > "continuous distribution" in terms roughly corresponding to >> > "symmetric," and then asserts that all distributions are either >> > symmetric or dichotomous (though without using either term). > > I must have missed something, but I don't see what the connection > between bisexuality-denial and delusions of symmetry. The argument is generally that if sexual orientation were a continuum rather than a dichotomy, values toward the middle of the continuum would necessarily be more common than values at the end points. One pop-sci treatment of sexual orientation (I can't remember if it was by Chandler Burr or Dean Hamer; I quit reading it as soon as I saw the assertion that statisticians defined a "continuous" distribution as one that was symmetric) claimed that this meant that sexual orientation could be viewed as an "on/off" switch. But my main point was that symmetry is more common in folkloric statistics than in the real world. > Indeed, I cannot recall *ever* coming across anybody making the > first > claim; under what circumstances is it usually made? The usual "odd" > assertion about sexual orientation that one does hear sometimes from > social conservatives is that there is no such thing as homosexual > orientation, such behaviour being supposedly entirely a matter of > choice; but that seems to be asserting the opposite, namely the > ubiquity of bisexuality. (Somebody commented, some time back, of a > politician who had made such a statement: "He has just 'outed' himself > as a bisexual living a voluntary heterosexual lifestyle.") > > So, anyhow: can you enlighten me? Where and why are these two odd > beliefs correlated? The particular argument I was referring to usually comes from at least nominally "pro-gay" sources, particularly those reporting on research into genetic bases for sexual orientation. The social conservatives mostly stay away from such sources. Yes, several people have commented on the fact that a lot of anti-gay arguments logically imply that everyone is bisexual, but then prejudiced people of all stripes have never been known for the logical consistency of their arguments; in fact, one of the easiest ways to tell that an antipathy is based on prejudice rather than realistic considerations is to observe that the beliefs purporting to support the negative attitude are contradictory. I have, for example, heard anti-gay arguments that *simultaneously* assert that 1) nearly everybody has a visceral repulsion to the thought of sexual activity between two men *and* 2) without strong taboos against sexual activity between men, most men would find the thought so attractive that they'd give up heterosexual sex and procreation would cease. But on the whole, most anti-gay arguments aren't based on probabilistic arguments, correctly interpreted or not, at all. It's generally those arguing against the antis, or taking a position of neutral inquiry, who try to use statistical arguments, and often stumble. Egregious overuse of convenience samples is probably the worst aspect; I've seen several "studies" where it was quite obvious from subject-matter knowledge that the criteria for inclusion in the sample were correlated with the outcome measures. Failure to control for other influences runs rampant (the famous study about the association between sexual orientation and birth order drew all its straight sample from Rotary-style service clubs and all its gay sample from activist groups). The real difficulty, of course, is the expense of getting an adequate-sized random sample of gay men, but too many researchers have engaged in "cargo-cult science" as an alternative. But I digress. Persons with "a little bit of knowledge" about probability really do seem to conflate the concepts of continuity, symmetry, unimodality, and normality, just as, as was the topic of a recent thread, they seem to conflate independence and mutual exclusivity, and I think these confusions need to be cleared up as soon as they arise in order to prevent "superstitious learning." I see income distribution as a good, accessible, real-world example of a distribution that's continuous but not symmetric. What would be good similar examples for distributions that are symmetric but not normal (for students who aren't yet sophisticated enough for the Cauchy distribution to be a good example)? Dice sums would be an obvious choice (though of course they converge to normal as the number of throws increases), but I think more are needed. . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
