1. Department of Applied Statistics; King Mongkut's University of Technology North Bangkok; Bangkok 10800 Thailand
2. School of Mathematics & Southampton Statistical Sciences Research Institute; University of Southampton; Southampton SO17 1BJ U.K.
3. Department of Paediatric Surgery; Southampton General Hospital; Southampton SO16 6YD U.K.
4. Statistics and Quantitative Methods, Faculty of Psychology and Sports Science; University of Münster; Muenster Germany