Error: Groupsbutnotwithinasubgroupbecausetheuij'sformembersofgroupishareai.wecanwritethecorrelationbetweenanytwoobservationsinthesamegroupas=cor(yij;yij0)=2a 2a 2e:aresultthatfollowsdirectlyfromtheusuald - PowerPoint Presentations and PDF Documents