David W. Allen is the GIS manager for the City of Euless, Texas. He has taught at Tarrant County College since 1999, where he helped found one of the first GIS degree programs in Texas and establish a state standard for GIS degree programs. He is the author of GIS Tutorial 2: Spatial Analysis Workbook (Esri Press, 2010) and Getting to Know ArcGIS ModelBuilder (Esri Press, 2011).
Jeffery M. Coffey, GISP, is currently the GIS manager for the Tarrant Regional Water District in Fort Worth, Texas, where he manages large GIS implementation, analysis, and integration projects. Coffey taught GIS classes at the University of North Texas and University of Texas at Arlington and helped establish an accredited GIS program at Tarrant County College where he currently teaches and serves on the GIS program's advisory board.