http://www.dartmouth.edu/~segregation/IndicesofSegregation.pdf
4. Original Jupyter Notebook
https://github.com/baolingz/PUI2017_bz882/blob/master/EC_bz882/EC_part1_bz882.ipynb
https://github.com/baolingz/PUI2017_bz882/blob/master/EC_bz882/EC_part2_bz882.ipynb