1. Department of Mathematics and Computer Science and Department of Quantitative Theory and Methods, Emory University, Atlanta, GA 30322, USA
2. Department of Geography, University of Nevada, Reno, NV 89557, USA
3. Department of Statistics, North Carolina State University, Raleigh, NC 27695, USA
4. Department of Math, Computer Science, and Statistics, Dordt College, Sioux Center, IA 51250, USA
5. Department of Biostatistics, University of Michigan, Ann Arbor, MI 48109, USA