I wish I had thought of that. It seems shady and I'm not sure the journal of neuroscience would have bought the argument, but hey...
-- Marc Carter, PhD Associate Professor and Chair Department of Psychology College of Arts & Sciences Baker University -- > -----Original Message----- > From: Jim Clark [mailto:j.cl...@uwinnipeg.ca] > Sent: Friday, January 07, 2011 1:30 PM > To: Teaching in the Psychological Sciences (TIPS) > Subject: RE: [tips] Don't Be Surprised If Your Physics > Colleagues Snicker When They Pass You In the Hall > > Hi > > But one-tailed is used generally (figuratively?) to refer to > directional alternative hypotheses (e.g., u1 > u2), and the > standard F test is non-directional (i.e., u1>u2 OR u2>u1), > even though it only involves (literally) one-tail of the > distribution. Assuming only two groups or a single df > contrast (e.g., linear), the directional F would have a p of > .07/2 = .035. > > If you want to have some "fun" with students, try to explain > to them why they need to look up the critical value of F for > .10 to do a directional (i.e., figurative one-tail) test, > although it does help for them to think of the t distribution > folded over and that t**2 = F. > > Take care > Jim > > James M. Clark > Professor of Psychology > 204-786-9757 > 204-774-4134 Fax > j.cl...@uwinnipeg.ca > > >>> Marc Carter <marc.car...@bakeru.edu> 07-Jan-11 11:45 AM >>> > > Ever since one of my grad faculty asked me to do a one-tailed > F-test, I hate one-tailed tests. > > I'm serious -- he really did. The probability of getting the > F we got was .07, and he said "Can't you do a one-tailed > test?" I explained -- calmly, I believe -- that F *is* > effectively a one-tailed test... > > m > > -- > Marc Carter, PhD > Associate Professor and Chair > Department of Psychology > College of Arts & Sciences > Baker University > -- > > > -----Original Message----- > > From: Jim Clark [mailto:j.cl...@uwinnipeg.ca] > > Sent: Friday, January 07, 2011 11:27 AM > > To: Teaching in the Psychological Sciences (TIPS) > > Subject: RE: [tips] Don't Be Surprised If Your Physics Colleagues > > Snicker When They Pass You In the Hall > > > > Hi > > > > I think of one-tailed (or Abelson's 1.5 tailed) tests as a kind of > > quasi-bayesian adjustment to the standard non-directional > test. That > > is, given empirical or theoretical grounds for expecting an > outcome in > > one direction, then one needs less evidence from the present study > > before moving in that direction. I also sometimes use a perceptual > > metaphor ... primed to expect some stimulus (e.g., meeting > someone in > > a crowded room), one needs less perceptual input before identifying > > the person. > > > > Also, it would appear that the same issues would arise with planned > > versus post hoc comparisons. That is, post hoc requires some > > adjustment for multiple tests, whereas planned may not > because of the > > expectation of a predicted pattern. > > > > Take care > > Jim > > > > James M. Clark > > Professor of Psychology > > 204-786-9757 > > 204-774-4134 Fax > > j.cl...@uwinnipeg.ca > > > > >>> "Bourgeois, Dr. Martin" <mbour...@fgcu.edu> 07-Jan-11 > 11:06 AM >>> > > Robert Abelson, in his excellent book Statistics as Principled > > Argument, advocates the use of what he calls a > one-and-a-half tailed > > test for directional predictions; for example, you could > set the alpha > > level at .04 in the tail of the predicted direction and .01 in the > > unpredicted direction. > > I always thought that was a neat idea, but I've never seen > anyone use > > it. > > > > ________________________________________ > > From: sbl...@ubishops.ca [sbl...@ubishops.ca] > > Sent: Friday, January 07, 2011 11:04 AM > > To: Teaching in the Psychological Sciences (TIPS) > > Subject: Re: [tips] Don't Be Surprised If Your Physics Colleagues > > Snicker When They Pass You In the Hall > > > > On 6 Jan 2011, I wrote in response to Martin Bourgeois pointing out > > that Bem used one-tailed tests: > > > > > That's interesting, disturbing, in fact. I've long argued > that one- > > > tailed tests are almost uniformly misused in psychology and > > should be > > > banned. Making a one-sided prediction is insufficient > justification. > > > One should only be allowed to use a one-tailed test if one can > > > plausibly argue that not only do I not predict a result in > > the "wrong" > > > tail, but that if such a perverse result occurred, it would > > either be > > > meaningless or of no interest at all. > > > > I am happy to report that a paper hot off the press (or do > they not do > > that any more?), in what appears to be a brand-new journal, has an > > excellent opinion piece which fully supports my view above. > How they > > got it into print so quickly after reading my post, I'll never know. > > > > The paper is this: > > > > Ruxton, G, and Neuhauser, M. (2010). When should we use one-tailed > > hypothesis testing? Methods in Ecology and Evolution, 1, 114-117. > > > > After giving a great example of the tangled mess an unwary > researcher > > is faced with when a one-tailed test goes rogue, they say this: > > > > "On the basis of their statistical test, the scientist has > no grounds > > for treating an experiment where the birds having a spectacular > > adverse reaction to the supplement any differently from the birds > > having no reaction. This philosophical lack of ability to act in > > response to unexpected results is the cost of one-tailed testing". > > > > Amen! Cut your costs! Help stamp out one-tailed tests! > > > > They also say "We rarely find ourselves in a position where we are > > comfortable with using a one-tailed test", and later, > "Use of one- > > tailed testing is more common than we would expect" [in ecology > > journals], They report that none of these uses involved a > satisfactory > > explanation. > > > > The authors' summary, in modest and restrained language, > offers this > > good guide for the perplexed: > > ---------------------------- > > Summary > > > > 1. Although one-tailed hypothesis tests are commonly used, clear > > justification for why this approach is used is often missing > > frompublished papers. > > > > 2. Here we suggest explicit questions authors should ask of > themselves > > when deciding whether or not to adopt one-tailed tests. > > > > 3. First, we suggest that authors should only use a > one-tailed test if > > they can explain why they are more interested in an effect in one > > direction and not the other. > > > > 4. We suggest a further requirement that adoption of one-tailed > > testing requires an explanation why the authors would treat a large > > observed difference in the unexpected direction no > differently from a > > difference in the expected direction that was not strong enough to > > justify rejection of the null hypothesis. > > > > 5. These justifications should be included in published > works that use > > one-tailed tests, allowing editors, reviewers and readers > the ability > > to evaluate the appropriateness of the adoption of > one-tailed testing. > > > > 6. We feel that adherence to our suggestions will allow > authors to use > > one-tailed tests more appropriately, and readers to form their own > > opinion about such appropriateness when one-tailed tests are used. > > ------------------------- > > > > > > Stephen > > > > -------------------------------------------- > > Stephen L. Black, Ph.D. > > Professor of Psychology, Emeritus > > Bishop's University > > Sherbrooke, Quebec, Canada > > e-mail: sblack at ubishops.ca > > --------------------------------------------- > > > > --- > > You are currently subscribed to tips as: mbour...@fgcu.edu. > > To unsubscribe click here: > > http://fsulist.frostburg.edu/u?id=13390.2bbc1cc8fd0e5f9e0b91f0 > > 1828c87814&n=T&l=tips&o=7744 > > or send a blank email to > > leave-7744-13390.2bbc1cc8fd0e5f9e0b91f01828c87...@fsulist.fros > > tburg.edu > > --- > > You are currently subscribed to tips as: j.cl...@uwinnipeg.ca. > > To unsubscribe click here: > > http://fsulist.frostburg.edu/u?id=13251.645f86b5cec4da0a56ffea > > 7a891720c9&n=T&l=tips&o=7746 > > or send a blank email to > > leave-7746-13251.645f86b5cec4da0a56ffea7a89172...@fsulist.fros > > tburg.edu > > > > --- > > You are currently subscribed to tips as: marc.car...@bakeru.edu. > > To unsubscribe click here: > > http://fsulist.frostburg.edu/u?id=13029.76c7c563b32ad9d8d09c72 > > a2d17c90e1&n=T&l=tips&o=7748 > > or send a blank email to > > leave-7748-13029.76c7c563b32ad9d8d09c72a2d17c9...@fsulist.fros > > tburg.edu > > > > The information contained in this e-mail and any attachments > thereto ("e-mail") is sent by Baker University ("BU") and is > intended to be confidential and for the use of only the > individual or entity named above. 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