Black-white wealth gap post

[MaxGhenis]

For MLK Day or sometime in February (Black history month)

Similar to my June 2020 piece but with (a) new SCF data, (b) plotly, (c) potentially other wealth metrics (like K-S test's D statistic??)

See also #53 on the income side (I think income and wealth would be worth separating). cc @ngpsu22

[MaxGhenis]

Calculating K-S test D statistic with weighted data in Python: https://stackoverflow.com/a/40059727/1840471

scf package: https://github.com/PSLmodels/scf

Code/notebook behind June post: https://github.com/UBICenter/black_ubi