Hot areas can be depicted using bounded areas such as polygons (e.g., see choropleth and standard deviation ellipse maps discussed in the sections below). However, analysts need to be aware that these bounded areas are artificial. Eck et al. (2005) argue that criminal activity does not necessarily conform to geographic boundaries. As such, hot area maps are not useful for showing crime patterns that cross boundaries (Eck et al., 2005). Boba (2005) also points out that these boundaries are usually artificially created administrative or political boundaries, which are constant or static (Eck et al., 2005). Analytical methods such as grid cell mapping or density analysis (discussed below) can be used to compensate for this limitation. These hot areas could develop at the block level, a set of blocks, neighborhoods, schools, and so forth. They might be affected by natural boundaries (rivers, cliffs, forests, etc.), government boundaries, man-made boundaries (highway, walls, fences, etc.), and social boundaries like gang territories.