Predicting group-level outcome variables from variables measured at the individual level: a latent variable multilevel model
Psychological Methods (2007) - Comment
pubmed: 17402811  doi: 10.1037/1082-989x.12.1.45  issn: 1082-989x  issn: 1939-1463 

Marcel A. Croon, Marc J. P. M. Van Veldhoven