Whereas one line of recent neighborhood research has placed an emphasis on zooming into smaller units of analysis such as street blocks, another line of research has suggested that even the meso-area of neighborhoods is too narrow and that the area surrounding the neighborhood is also important. The authors found that racially and ethnically homogenous blocks within heterogeneous block groups have the most crime. Source: http://onlinelibrary.wiley.com/doi/10.1111/1745-9125.12074/abstract