Re: Marijuana
On Sat, 23 Jun 2001 23:35:06 GMT, Tetsuo [EMAIL PROTECTED] wrote: in article [EMAIL PROTECTED], Tetsuo at [EMAIL PROTECTED] wrote on 24-06-2001 00:17: in article [EMAIL PROTECTED], David C. Ullrich at [EMAIL PROTECTED] wrote on 23-06-2001 16:06: [obvious jokes' [explanation of why the assertions in the obvious jokes are wrong] [...] Sorry for that indeed, ppl actually have this kind of opinion on this sometimes so I assumed I encountered just another one and got irritated. I should've realized the poster would not spout such stupidity in a serious manner though, of course...heh, certainly not in this ng. No problem, actually I enjoyed reading it. Slightly disappointing that you finally figured out I was being sarcastic - when I read your post I was looking forward to stringing you along a bit. Well, sorry again David C. Ullrich * Sometimes you can have access violations all the time and the program still works. (Michael Caracena, comp.lang.pascal.delphi.misc 5/1/01) = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
Re: Marijuana
On Sat, 23 Jun 2001 21:12:40 -0700, Chas F Brown [EMAIL PROTECTED] wrote: David C. Ullrich wrote: [...] In the back-of-envelope calculations I did, this is really the key missing information. If heart attacks are evenly distributed through the day, while MJ smoking (as far as I know!) clearly isn't for most users, then the temporal correlation is going to be alot more marked. Or they tend to smoke before meals (I knew some people like that years ago in college) and tend to have heart attacks after meals. Or they tend to smoke when they start to feel little chest pains, as someone suggested. But you're reading something into what I said, that I didn't say - I'm not saying that the data imply that smoking _causes_ an increased your risk of heart attack in the hour after smoking (although this evidence would support further investigation that that _may_ be the case). Ok. [...] David C. Ullrich * Sometimes you can have access violations all the time and the program still works. (Michael Caracena, comp.lang.pascal.delphi.misc 5/1/01) The scary thing is - he's right. That's one scary thing - in fact there are places in Windows95 where the system _regularly_ creates GPF's; something to do with thunking or something. But the scary thing about the quote is that the guy was advocating _hiding_ AV's in programs we write instead of fixing them. AV's can be hard to debug - the eaiest way is to make certain they don't arise in the first place. And given this guy's attitude, one of the steps involved in ensuring that your code contains no hard-to-debug AV's is making sure you never use anything he wrote. Hence the sig - it's a public-service thing. (Ooops! Netscape just locked up - time to reboot again...) Cheers - Chas --- C Brown Systems Designs Multimedia Environments for Museums and Theme Parks --- David C. Ullrich * Sometimes you can have access violations all the time and the program still works. (Michael Caracena, comp.lang.pascal.delphi.misc 5/1/01) = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
Help with stats please
Hi. I am teaching educational statistics for the first time, and although I can go on at length about complex statistical techniques, I find myself at a loss with this multiple choice question in my test bank. I understand why the range of (b) is smaller than (a) and (c), but I can't figure out how to prove that it is smaller than (d). If you can explain it to me, I will be humiliated, but grateful. 1. Which one of the following classes had the smallest range in IQ scores? A) Class A has a mean IQ of 106 and a standard deviation of ll. B) Class B has an IQ range from 93 to 119. C) Class C has a mean IQ of 110 with a variance of 200. D) Class D has a median IQ of 100 with Q1 = 90 and Q3 = 110. The test bank says the answer is b. Melady = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
Re: Help with stats please
At 12:20 PM 6/24/01 -0700, Melady Preece wrote: Hi. I am teaching educational statistics for the first time, and although I can go on at length about complex statistical techniques, I find myself at a loss with this multiple choice question in my test bank. I understand why the range of (b) is smaller than (a) and (c), but I can't figure out how to prove that it is smaller than (d). If you can explain it to me, I will be humiliated, but grateful. 1. Which one of the following classes had the smallest range in IQ scores? of course, there is nothing about the shape of the distribution of any class ... so, does the item assume sort of normal? in fact, since each of these classes is probably on the small side ... it would be hard to assume that but, for the sake of the item ... pretend in addition, it does not say to assume the population of IQ scores has mean = 100 and sd about 15 ... so, whether this plays a role or not, i am not sure BUT ... A) Class A has a mean IQ of 106 and a standard deviation of ll. at least about 2 units of 11 = 22 on each side of 106 ... range about 45 or so or more B) Class B has an IQ range from 93 to 119. well, range here is about 26 ... less than in A for sure C) Class C has a mean IQ of 110 with a variance of 200. variance of 200 means an sd about 14 ... so 2 units of 14 = 28 on each side of 110 ... range must be 50 or more ... similar to A but, more than C D) Class D has a median IQ of 100 with Q1 = 90 and Q3 = 110. 25th PR = 90 and 75PR = 110 ... IF we assumed the class was ND ... then the mean would be about 100 too ... and since -1 for SD below the mean and +1 SD above the mean would give your roughly the 16th PR and 84th PR ... Q1 and Q3 are NOT that far out ... so, the SD must be at least 10 or more ... thus, 2 units of at least 10 = 20 on either side of 100 = range of at least about 40 ... probably less than A or C ... but, more than B ... B is probably the best of the lot BUT, i am NOT sure what the real purpose of this item is ... The test bank says the answer is b. Melady = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ = _ dennis roberts, educational psychology, penn state university 208 cedar, AC 8148632401, mailto:[EMAIL PROTECTED] http://roberts.ed.psu.edu/users/droberts/drober~1.htm = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
Re: cigs figs
- re: some outstandingly confused thinking. Or writing. On Sat, 23 Jun 2001 15:25:31 GMT, mackeral@remove~this~first~yahoo.com (J. Williams) wrote: [ snip; Slate reference, etcetera ] ... My mother was 91 years old when she died a year ago and chain smoked since her college days. She defended the tobacco companies for years saying, it didn't hurt me. She outlived most of her doctors. Upon quoting statistics and research on the subject, her view was that I, like other do gooders and non-smokers, wanted to deny smokers their rights. What statistics would her view quote? to show that someone wants to deny smokers 'their rights'? [ Hey, I didn't write the sentence ] I just love it, how a 'natural right' works out to be *exactly* what the speaker wants to do. And not a whit more. (Thomas and Scalia are probably going to give us tons of that bad philosophy, over the next decades.) What rights are denied to smokers? You know, you can't build your outhouse right on the riverbank, either. Obviously, there is a health connection. How strong that connection is, is what makes this a unique statistical conundrum. How strong is that connection? Well, quite strong. I once considered that it might not be so bad to die 9 years early, owing to smoking, if that cut off years of bad health and suffering. Then I realized, the smoking grants you most of the bad health of old age, EARLY. (You do miss the Alzheimer's.) One day, I might give up smoking my pipe. What is the statistical conundrum? I can almost imagine an ethical conundrum. (How strongly can we legislate, to encourage cyclists to wear helmets?) I sure don't spot a statistical conundrum. Is this word intended? If so, how so? -- Rich Ulrich, [EMAIL PROTECTED] http://www.pitt.edu/~wpilib/index.html = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
Re: Help with stats please
On Sun, 24 Jun 2001, Melady Preece wrote in part: I am teaching educational statistics for the first time, and although I can go on at length about complex statistical techniques, I find myself at a loss with this multiple choice question in my test bank. I understand why the range of (b) is smaller than (a) and (c), but I can't figure out how to prove that it is smaller than (d). 1. Which of the following classes had the smallest range in IQ scores? A) Class A has a mean IQ of 106 and a standard deviation of ll. B) Class B has an IQ range from 93 to 119. C) Class C has a mean IQ of 110 with a variance of 200. D) Class D has a median IQ of 100 with Q1 = 90 and Q3 = 110. The test bank says the answer is b. Right. Since you're happy that range(B) range(A) and range(B) range(C), I'll focus on (B) vs. (D). In (B), the entire _range_ is from 93 to 119: 26 (or 27, depending on how you choose to define range) points. In (D), the central half of the distribution is from 90 to 110: the interquartile range (IQR) is 20 points, symmetric about the median; the full range must therefore be greater than 20. Now, _if_ the distribution is normal (which may be what we were to assume from the allegation that these are IQ scores; although as Dennis has pointed out, ille non sequitur -- unless these are rather large classes AND NOT SELECTED BY I.Q. (or by any variable strongly related to I.Q.)), then 10 points from Q1 to median (or from median to Q3) represents 0.67 standard deviation, which implies a standard deviation of about 15, which is larger than the standard deviation in (A) and slightly larger than that in (C). However, we need not invoke the normal distribution. We observe that the distribution in (D) is at least approximately symmetric (insofar as the quartiles are equidistant from the median). If we may assume also that the distribution is unimodal (which I should think reasonable), it then follows (from the tailing off of distributions as one approaches the extremes) that the distance from minimum to Q1 (and the distance from Q3 to maximum) is greater than the distance from Q1 to median (or median to Q3). This implies that the range of the distribution exceeds twice the interquartile range: that is, range(D) 2*20 = 40. Since the range in (B) is only 26, clearly the range of (B) is less than the range of (D). If any part of this argument remains unclear, I'd be happy to attack it again. A rough sketch should make things pretty obvious, but it's a bit of a nuisance to draw pictures in ASCII characters! --DFB. Donald F. Burrill [EMAIL PROTECTED] 184 Nashua Road, Bedford, NH 03110 603-471-7128 = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
