Hi all, in R the glm.nb models return a theta value, the aggregation parameter for negative binomial distributions. Crawly in his S-Plus book talks about the clumping (aggregation) parameter k. Are these two things (theta and k) different, and if so, what would be the relationship between the two? Thank you in advance, Johan -- Johan Kotze Department of Biological and Environmental Sciences PO Box 65 (Biocenter 3, Viikinkaari 1) FI-00014, University of Helsinki Helsinki, FINLAND Tel: +358 (0)9 191 57707 Fax: +358 (0)9 191 57694 E-mail: johan.kotze at helsinki.fi Editor-in-Chief, Journal of Negative Results - EEB (www.jnr-eeb.org) www.helsinki.fi/ml/ekol/spatial_ecology.html www.helsinki.fi/science/globenet/