My comments should have been addressed to Matheus, not Edwin. I apologize.
Jim On Fri, Jul 10, 2009 at 11:50 AM, James Crants <[email protected]> wrote: > Edwin, > > My issue with such a small sample size would not be low power, but low > reliability. If you show me the result for a single replicate, I have no > confidence whatsoever that that result is typical for the treatment. Just > try calculating the 95% confidence intervals around your results. If you > can even find the 95% confidence interval for a treatment with a single > replicate, you've done something wrong. I'm surprised only one reviewer > complained about your sample sizes and that you didn't need to correct this > to publish the paper, especially since it sounds like it would have been > logistically simple to increase the replication. > > I am also surprised G*power 3 would say that an experiment with just one or > two replicates per treatment had near-maximum power. Were you testing for > the power to detect differences of the magnitude you actually observed? If > so, of course the power would be around 1, if your p-values were low (if > your ANOVA actually detected a significant difference, its power to detect > that difference must be high). For a power test, you want to know the power > of your experimental design to detect the smallest difference you would find > biologically meaningful. > > Jim Crants > > On Fri, Jul 10, 2009 at 3:49 AM, Edwin Cruz-Rivera < > [email protected]> wrote: > >> Let me rephrase: out of 12 treatments, 10 had one replicate and 2 had 2. >> However, these were not natural lakes or transects in geographic zones >> that constrained replication. These were 100 ml bottles on a table. >> Sorry for the oversimplification. >> >> Edwin >> >> >> > Changing a little the topic, I have a question about the statement of >> > Edwin. He wrote: >> > "If the statistics are grossly inappropriate (for example running an >> > ANOVA with 12 treatments, but only 1 or two replicates per treatment), >> > adequate peer review was clearly not in place." >> > Well, I published a paper in which I used 2 way ANOVA with a total of 18 >> > groups and 2 replicates per groups. It was peer reviewed, and one of the >> > reviewers complained about my statistics, asking for measurements of >> > power, perhaps with the expectation that that particular test would have >> > no enough power to draw any conclusions. I used a software to measure >> the >> > power of the test (G*power 3), and found that power was the maximum >> > possible (1.00) for the effects due to factors 1 and 2, and 0.99 for the >> > interaction effect.Was my test flawed? It was peer reviewed! >> > Best, >> > >> > Matheus C. Carvalho >> > >> > Postdoctoral Fellow >> > Research Center for Environmental Changes >> > >> > Academia Sinica >> > >> > Taipei, Taiwan >> > >> > --- Em qui, 9/7/09, Edwin Cruz-Rivera <[email protected]> >> > escreveu: >> > >> > De: Edwin Cruz-Rivera <[email protected]> >> > Assunto: Re: [ECOLOG-L] "real" versus "fake" peer-reviewed journals >> > Para: [email protected] >> > Data: Quinta-feira, 9 de Julho de 2009, 10:37 >> > >> > I believe one of the original questions was how to discern reputable >> > journals from those that publish dubious or biased results...or do not >> > accomplish proper peer review. I can point to a couple of red flags >> that >> > can be noticed without too much effort and I have observed: >> > >> > 1) If the articles in the journal come mostly from the same institution >> in >> > which the editor in chief is located, chances are the buddy system has >> > overwhelmed objectivity...especially if the editor is a co-author in >> most. >> > >> > 2) If orthographic and syntax errors are widespread, probably the review >> > process was not thorough. >> > >> > 3) If the statistics are grossly inappropriate (for example running an >> > ANOVA with 12 treatments, but only 1 or two replicates per treatment), >> > adequate peer review was clearly not in place. >> > >> > Now these may look like extreme cases, but I have seen too many examples >> > similar to the above to wonder how widespread these cases are. I have >> > even received requests to review papers for certain journals in which I >> > have been asked to be more lenient than if I was reviewing for a major >> > journal. This poses a particular dilemma: Is all science not supposed >> to >> > be measured by the same standards of quality control regardless of >> whether >> > the journal is institutional, regional, national or international? >> > I would like to think it should be... >> > >> > Edwin >> > ------------------------------------------------------------------ >> > Dr. Edwin Cruz-Rivera >> > Assist. Prof./Director, Marine Sciences Program >> > Department of Biology >> > Jackson State University >> > JSU Box18540 >> > Jackson, MS 39217 >> > Tel: (601) 979-3461 >> > Fax: (601) 979-5853 >> > Email: [email protected] >> > >> > "It is not the same to hear the devil as it is to see him coming your >> way" >> > (Puerto Rican proverb) >> > >> > >> > >> > >> > >> > >> ____________________________________________________________________________________ >> > Veja quais são os assuntos do momento no Yahoo! +Buscados >> > http://br.maisbuscados.yahoo.com >> > >> > > > > -- > James Crants, PhD > Scientist, University of Minnesota > Agronomy and Plant Genetics > Cell: (734) 474-7478 > -- James Crants, PhD Scientist, University of Minnesota Agronomy and Plant Genetics Cell: (734) 474-7478
