Re: comparing 2 slopes
Mike, Yes, you are correct. A purist might say that you didn't actually prove that the slopes are the same, only that you failed to demonstrate a significant difference between them (because non-significant parameters can become significant with more data). However, your interpretation is correct and, also, including an interaction term to examine its statistical significance is the best approach. Ellen Hertz "Mike Tonkovich" <[EMAIL PROTECTED]> wrote in message news:3b20f210_1@newsfeeds... > Was hoping someone might be able to confirm that my approach for comparing 2 > slopes was correct. > > I ran an analysis of covariance using PROC GLM (in SAS) with an interaction > statement. My understanding was that a nonsignificant interaction term > meant that the slopes were the same, and vice versa for a significant > interaction term. Is this correct and is this the best way to approach this > problem with SAS? Any help would certainly be apprectiated. > > Mike Tonkovich > > -- > Michael J. Tonkovich, Ph.D. > Wildlife Research Biologist > ODNR, Division of Wildlife > [EMAIL PROTECTED] > > > > > -= 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 and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
Re: Double mediation
> From: [EMAIL PROTECTED] (Sylvia J. Hysong, Ph.D.) > Organization: http://groups.google.com/ > Newsgroups: sci.stat.edu,comp.soft-sys.stat.spss > Date: 5 Jul 2001 14:35:24 -0700 > Subject: Double mediation > > Hello, > > I'm hoping someone can help me with this. I have looked at a > multitude of resources including the David Kenny page, this and other > newsgroups, Pedhazur (1982), Cohen & Cohen (1983), and Darlington > (1990?), to no avail. I am hoping someone can direct me to the right > resource. I am trying to conduct a test of double mediation. In > other words, I am trying to test the hypothesis that x-->z1-->z2-->y. > Is there a way to do this (and if so, what is it?), or must I result > to a path analysis or a structural equation model? > > Thanks in advance for any help. Would this do it? Estimate a regression model with y as the dependent and x, z1 and z2 as independents. That gives the direct path from z2-->y, controlling for x and z1. Then a second model with z2 as the dependent and x, and z1 as independents. That gives the direct path from z1-->z2, controlling for x. The a third model with z1 as the dependent and x as the independent. = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
Conference Intro Statistics Teachers
+++ LAST CALL ! ! ! ! IF YOU HAVEN'T ALREADY MADE PLANS TO ATTEND IT'S NOT TOO LATE !REGISTER TODAY ! Fifth Annual BEYOND THE FORMULA Statistics Conference - Introductory Statistics For A New Century: Integrating New Curriculum Ideas and Modern Techniques into Our Beginning Statistics Course This conference is for ALL teachers of Introductory Statistics, from those teaching the first time to the experienced teacher. There are sessions planned for all. DATE: Thursday, August 2, 2001, 8:00 AM to 8:15 PM Friday, August 3, 2001, 8:00 AM to 3:30 PM LOCATION: Monroe Community College's Damon City Campus 228 East Main Street, Rochester, NY 14604 The $135 registration fee includes 2 breakfasts, 2 lunches, dinner, breaks, materials. VISIT OUR WEBSITE: www.monroecc.edu/depts/math/beyond1.htm to find out about the Beyond The Formula conferences: History, 2001 Program Details, Registration Information and Form, Hotel and Travel Information. IF YOU REQUIRE FURTHER INFORMATION: E-MAIL [EMAIL PROTECTED] OR CALL 716-292-2931 +++ = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
Late Absentee Ballot Acceptance Rates in Florida
In an exhaustive investigation, the N.Y. Times has studied the acceptance pattern of absentee ballots which arrived in Florida following the November election. In an analysis of the 2,490 ballots from Americans living abroad that were counted as legal votes after The Times found 680 questionable votes. Although it is not known for whom the flawed ballots were cast, 4 out of 5 were accepted in counties carried by Mr. Bush, The Times found. The counties carried by Mr. Gore accepted 20% that had no evidence they were mailed on or before Election Day. Counties carried by Mr. Bush accepted 60% of the same kinds of ballots. Bush counties were 4 times as likely as Gore counties to count ballots lacking witness signatures and addresses. Since the envelopes containing the absentee ballots were separated from the ballots themselves, no information about the voter was available: "The Times asked Gary King, a Harvard expert on voting patterns and statistical models, what would have happened had the flawed ballots been discarded. He concluded that there was no way to declare a winner with mathematical certainty under those circumstances. His best estimate, he said, was that Mr. Bush's margin would have been reduced to 245 votes. Dr. King estimated that there was only a slight chance that discarding the questionable ballots would have made Mr. Gore the winner. " It just gets curiouser and curiouser. If interested, the complete article is online: http://www.nytimes.com/2001/07/15/national/15BALL.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: Alscal vs. NCSS
NMDS can get trapped in local minima. It is advisable to use several random configurations as starting points and choose the solution with the lowest Stress (Kruskal or Young's - I don't have a preference). I checked SPSS and it doesn't have a random initial configuration that I could see. That is an option with the Bell labs KYST-2 program that I use (an old Fortran version) = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
Alscal vs. NCSS
Dear all, I have two questions regarding MDS: 1. I have run an NMDS through Alscal (SPSS) and NCSS, and the representations of the variables on a 2-dimensional map look completely different. As far as I can tell, I am using the same procedure in both algorhythms, so I cannot understand why I get different results, and which one I should prefer as more accurate. 2. Does anyone know which of the following two stress indices should be used with data from psychometric instruments (e.g. personality questionnaire): Kruskal's or Guttman-Lingoes? Thank you Niko Tiliopoulos = Instructions for joining and leaving this list and remarks about the problem of INAPPROPRIATE MESSAGES are available at http://jse.stat.ncsu.edu/ =
