abstracted ggplot and dplyr homework from lessons, and added a new assignment for essential statistics ... adjusted the navigation in _site.yml to reflect these changes
thanks @vpnagraj. didn't fully review stats HW, but will do. i imagine the vandy biostats data has low risk of disappearing. however, do you think it's worth archiving a copy here locally?
abstracted ggplot and dplyr homework from lessons, and added a new assignment for essential statistics ... adjusted the navigation in _site.yml to reflect these changes