Returning to the original topic:
I have continued to collect data. I do another set of data every 15ish days. As I do more reviews, there are two clear groups: Beluaterra, Dwilight, and Far East Island tend to swap off the "top positions" (based on activity and high-activity rates and changes in them, new registrations, changes in number of active or highly active players), while East Island, Atamara, and the Colonies continue to occupy the lowest positions.
A curious thing is that I cannot identify any relationship between levels of 3-day activity and retention. I expected to find that active continents had higher retention. High-activity also has little predictive usefulness (plus, high activity fluctuates so widely that its weekly changes are larger than its long-term changes).
East Island barely even managed to break even on registrations this time around (1.5% increase), while FEI and Dwilight saw very significant growth.*
*FEI and Dwilight also just had multi-cheating issues discovered. However, even if all multi-accounts are discounted, Dwilight still dominates the field for registrations, and FEI and Dwilight both remain leaders, though FEI falls to closer to Atamara and Beluaterra