Update: I tried regressing on the ordinal position of the world records and found a much better fit, and better (above baseline!) forecasts of the last WR of each category.
This makes me update further towards the hypothesis that date is a bad predictive variable. Sadly this would mean that we really need to track whatever the index in WR is correlated with (presumably the cumulative number of runs overall by the speedrunning community).
Linear regression with logarithmic transforms on both axis
Update: I tried regressing on the ordinal position of the world records and found a much better fit, and better (above baseline!) forecasts of the last WR of each category.
This makes me update further towards the hypothesis that
dateis a bad predictive variable. Sadly this would mean that we really need to track whatever the index in WR is correlated with (presumably the cumulative number of runs overall by the speedrunning community).