Contributing to the discussion on textiles: I agree with Donald that the "shirt problem" is suitably modeled using a within-subjects repeated measures design. This, of course, assumes that "their heart rate, skin and core temperature etc." were assessed at multiple time points after wearing one of the four shirt types.
It is also possible to reconfigure the problem by framing the "type of shirt" as four different groups in a simple ANOVA but you would unnecessarily get inflated variance estimates. In this situation, a repeated measures design is probably more powerful because it accounts for correlations among the within-subject variables. Remember, in both cases, you should be careful to check for normality because with only 8 cases normality is often an issue. My guess is that Paige did not understand the problem correctly. The author wrote, that the "same 8 subjects wore the shirts and performed some physical activity." At first, I also thought there was only 1 assessment conducted. Jeff --------------------------------------------------------------- UCLA Cousins Center for Psychoneuroimmunology (Affiliated with the Neuropsychiatric Institute and Department of Psychiatry and Biobehavioral Sciences) 300 UCLA Medical Plaza, Room 3148 Los Angeles, CA 90095-7057 Tel: 310-267-4389 Fax: 310-794-9247 E-mail: [EMAIL PROTECTED] Web: http://www.cousinspni.org/ ATTENTION The information contained in this message may be legally privileged and confidential. It is intended to be read only by the individual or entity to whom it is addressed or by their designee. If the reader of this message is not the intended recipient, you are on notice that any distribution of this message, in any form, is strictly prohibited. If you have received this message in error, please immediately notify the sender and delete or destroy any copy of this message. -----Original Message----- From: Donald Burrill [mailto:[EMAIL PROTECTED] Sent: Thursday, January 29, 2004 9:11 AM To: Paige Miller Cc: [EMAIL PROTECTED] Subject: Re: [edstat] one way ANOVA or repeated measures ANOVA On Thu, 29 Jan 2004, Paige Miller wrote in part, in response to Bruce Weaver: > I think it all boils down to terminology differences, as I can't argue > with your ANOVA table. I think of this as a full factorial in A and > B, with a blocking variable named "subject". Yes, that'a a logical way of looking at it (although probably not the first way of describing it that would leap to a psychologists's mind!). > As I said in my first post on this topic, I think of repeated measures > as you apply a "treatment" to an experimental unit, and then record > that experimental unit's value over time. For example, you give a drug > to a subject, then record a measurement of that subject at 1 day, 2 > days, 3 days, ... Perhaps that's an extremely narrow view of what > "repeated measures" is, but that's how I use the term. Exactly. In Archana's case, the experimental unit is a subject. Subject dons a garment, carries out some physical activity, and assorted variables are measured (whether before, during, or after the activity, or all three, was not specified). Subject sets this garment aside. After some time, subject then dons another garment, and the protocol is repeated. (Presumably enough time elapses between these repetitions for any lingering effects of the first activity -- fatigue, elevated heart rate, etc. -- to have dissipated; but this too was not specified.) This continues until all four garments have been used. Whether the interval between repetitions is one day, or more or less than a day, or even whether it's always the same interval, is probably irrelevant to the outcome, given that presumption. There may be some lurking issues about equivalence of garments, if a different set of garments is used for each subject. (A different set of issues -- having to do with laundering, e.g. -- arises if the same set of garments is used by all subjects, or even by more than one subject.) One gathers these issues are felt not to be important. -- DFB. ----------------------------------------------------------------------- Donald F. Burrill [EMAIL PROTECTED] 56 Sebbins Pond Drive, Bedford, NH 03110 (603) 626-0816 . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . ================================================================= . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
