I have also put this on sci.stat.edu for any comment. I am not sure if that is the right group.
Szasz <[EMAIL PROTECTED]> wrote: > Brian Sandle <[EMAIL PROTECTED]> wrote in message >news:<[EMAIL PROTECTED]>... [...] >> Rank each subject >> in order for social factors, extent of cocaine use in pregnancy, extent of >> hyperactivity at age four or more of resulting child. Then go to some >> source like Castellan (recent edition) which gives a formula for partial >> rank correlation with significance. It may not be a certain result, but if >> it shows something, then think out other means of investigation. > At some point, Brian, you have to consider the possibility that the > people who did these studies used the best statistical methods > available, Understanding of statistics is not very good, even at PhD level, yourself, szasz: and simply re-doing the study in different ways until they > get a result you agree with is not the way scientists do business. > By the way, a partial rank correlation (AKA Pearson product-moment > correlation) is generally considered the basis of all multivariate > statistical techniques. A partial rank correlation is _not_ also known as Pearson product-moment correlation. First mistake: The Pearson product-moment correlation is not a rank correlation. The Pearson product-moment correlation would be used for linear data, which are given scores and are found to be symmetrically spread above and below an average value. So it very often should not be used. Second mistake: The Pearson product-moment correlation is not a partial correlation. Though a table can be written up showing how the various variables correlate to one another, nothing is done mathematically to hold variables constant, which is the essence of partial correlation. When data are not evenly spread a _rank_ correlation is thought to be more robust. Data are not given scores, but just put in order from biggest to littlest. The Spearman rank correlation might then be used. That is not however a partial correlation. Its table shows hows how various things are correlated but does not hold mathematically hold any variable constant and so look deeper. The next step, a _partial_ rank correlation, was dealt with in Siegel's work on statistical method. But the technique was not advanced sufficiently to calculate any _significance_ figure. Later, Castellan re-did Siegel's book and introduced a significance calculation for partial rank correlation. He said it was not totally to be trusted, I think. When I was interested in the work of an MA psychology student I was provided through the newsgroups with a VAX based program which would do the calculations, though I did not find out how to use it on the VAX at that stage. What is available now? Linux or anything? The idea that your suggestion is anything more > than a distraction from the main point (e.g., that 'crack baby' > syndrome is essentially a made-up syndrome) is laughable. March on. I said `crack _baby_' is made up. I am waiting for Proctor's reply. The problems do not show till _after_ babyhood, when the developing executive funcitoning is trying to call up the releveant areas of the brain for that time. -- Brian Sandle. please remove `shell' from between @ and caverock to reply by e-mail. -----= Posted via Newsfeeds.Com, Uncensored Usenet News =----- http://www.newsfeeds.com - The #1 Newsgroup Service in the World! -----== Over 80,000 Newsgroups - 16 Different Servers! =----- . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
