48-Correspondence Analytical flaws in a continenta

48-Correspondence Analytical flaws in a continental-scale forest soil microbial diversity studyCorrespondence:Analyticalflawsinacontinental-scaleforestsoilmicrobialdiversitystudyLehoTedersoo1NatureCommunications8:15572doi:10.1038/ncomms15572(2017);Published6Jun2017Zhouetal.1recentlyaddressedcontinental-scalebiogeographicpatternsofsoilmicroorganisms.TheauthorssuggestedthatthemeanannualtemperatureratherthanotherenvironmentalpredictorsdrivethelatitudinalgradientofdiversityinsoilbacteriaandfungisampledfromsixpermanentstudyareasacrossNorthAmerica.HereIarguethattheirapproachisflawedbecauseofpseudoreplicateddesign,incorrectchoiceofstatisticaltoolsandoveroptimisticinterpretation.Fromeachofthesixsites,theauthorscollected21compositesoilcores(located1–400mapart)thatweretreatedasindependentsamplingunitstoinfercontinental-scalepatterns.Theauthorsthenusedsimpleregressionanalysestoaddressthedifferencesamongsamplesinsteadofnestingsampleswithinsitesorusingsitesascategoricalpredictors,thusoverestimating