On Wed, 2011-11-16 at 03:43 +0100, Gian Maria Niccolò Benucci wrote: > Hi all, > > I had 84 samples collected in 7 different sites. > In each sample were individuated the different fungal species and recorded. > I would test if exist a real difference between the sites and if exist a > sort of site effect that structure the fungal communities... > Then, I did adonis test > > > adonis(community.sq ~ location, data=env.table, permutations=999) > > Call: > adonis(formula = community.sq ~ location, data = env.table, permutations = > 999) > > Df SumsOfSqs MeanSqs F.Model R2 Pr(>F) > location 6 12.593 2.09886 6.8867 0.34922 0.001 *** > Residuals 77 23.467 0.30477 0.65078 > Total 83 36.060 1.00000 > --- > Signif. codes: 0 *** 0.001 ** 0.01 * 0.05 . 0.1 1 > > > > The significance is R2=0.349 at P=0.001 > Can I assure that exist a strong site effect in structuring the communities > in each site?
Depends. The test is one of no effect of `location`. You have found evidence against this hypothesis and thus could reject this hypothesis, instead accepting the alternative hypothesis that there is an effect of `location`. As to the strength of this effect? ~35% of the sums of squares can be explained by `location`. Substantially more of the variance remains unexplained. As I know nothing about your subject area, I am unable to comment further on the strength of the relationship. Seeing as many ecologists whose work I read would say an effect is significant if the p-value was >= 0.05. Not that I subscribe to this way or working, but by that criterion, you have identified a significant `location` effect. HTH G > > Thanks for helping, > > G. > > [[alternative HTML version deleted]] > > _______________________________________________ > R-sig-ecology mailing list > [email protected] > https://stat.ethz.ch/mailman/listinfo/r-sig-ecology -- %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% Dr. Gavin Simpson [t] +44 (0)20 7679 0522 ECRC, UCL Geography, [f] +44 (0)20 7679 0565 Pearson Building, [e] gavin.simpsonATNOSPAMucl.ac.uk Gower Street, London [w] http://www.ucl.ac.uk/~ucfagls/ UK. WC1E 6BT. [w] http://www.freshwaters.org.uk %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% _______________________________________________ R-sig-ecology mailing list [email protected] https://stat.ethz.ch/mailman/listinfo/r-sig-ecology
