I have a set of data that consists of a number of biological measurements. The columns are Time that runs from 01/01/2005 to 01/5/2007, Group which has 23 levels and postcode which is nested within group. This is a balanced panel but the number of postcodes differs within groups, from 15 to 400. The rest of this data consists of a number of columns of quantitative measures, largely counts. I would like to set this up as a dataframe but retain the time series element and the structural relations within the data. How can I do this in R? Whenever I try ts I end up with things out of order without the time series element.correctly represented Secondly assuming that I wish to regress temperature against vegetation and type how do I express this as a linear hierarchical model nesting postcode within group but keeping time as non nested (eg group x time) with calendar time as a group level predictor? Any help would be most appreciated. Graham Leask Kind regards Dr Graham Leask Economics and Strategy Group Aston Business School Aston University Aston Triangle Birmingham B4 7ET Tel: Direct line 0121 204 3150 Fax: 0870 759 8408 email g.leask@aston.ac.uk [[alternative HTML version deleted]]