The horizontal axis shows the go rating scale used by the EGD and the revised rating system.
The vertical axis shows units of log-odds per rating point.
The thick blue line is 1/a in a standard Elo rating system:
1/a = ρ(r) => ln(10) / 400
The red line is 1/a used by the EGD rating system:
1/a = ρ(r) => r < 2700 ? 20 / (4100 - r) : 1 / 70
The black line is a fit to 1/a observed in the EGD history:
1/a = ρ(r) => 0.0022 + 0.000025 * exp(rating / 440)