Dear all, I'm using the correlogram function in the spatial library to calculate spatial correlograms of radar data. However, I'm finding that the resulting values are often outside the range [-1,1], usually only at larger distances of separation. I'm not sure whether to be overly concerned about this, or dismiss it as some artefact of the data. Has anyone had similar experiences? Or know why this might be happening? Thanks Kechi
correlogram in spatial producing values outside [-1,1]
2 messages · Kechi Nzerem, Brian Ripley
It can happen. The covariance is produced from a set of pairs, and the variances from all the points. It usually indicates that too fine a binning has been used or that there is a trend in the data which has not been removed.
On Thu, 12 May 2005, Kechi Nzerem wrote:
I'm using the correlogram function in the spatial library to calculate spatial correlograms of radar data. However, I'm finding that the resulting values are often outside the range [-1,1], usually only at larger distances of separation. I'm not sure whether to be overly concerned about this, or dismiss it as some artefact of the data. Has anyone had similar experiences? Or know why this might be happening?
Brian D. Ripley, ripley at stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595