search for: absence_record

...and test datasets I realise I could do this by sorting my column of presences and absences and then taking a subsample of the required size from the rows containing presences then the rows containing absences and combining them. e.g. presence_records<-sample(1:117,size=75,replace=FALSE) absence_records<-sample(118:936,size=549,replace=FALSE) ss<-c(presence_records,absence_records) but... b) My samples are within video transects and due to the risk of autocorrelation within each transect, ideally it is by transect cluster that they will be randomly selected. (a point...