spatial processspatial samplingspcspearman brown formulaspearman estimatorspearman rank correlation coefficientspeciesspecific factorsspecific variancespecificationspecificityspecificity sensitivityspectralspectral analysisspectral decompositionspectral density functionspectral distributionspectral estimationspectral factorizationspectral functionspectral windowspheresphere packingspherical distributionspherical medianspherical regressionsphericityspike trainsspitzer rosen theoremspline functionsplit plot designspontaneous processspreadsprtspssspuriousspurious associationspurious correlationspurious dependencesquaresquare matrixsquare rootsqueeze significance testssessrsststability groupstabilizationstabilizerstable distribution