What does this equation mean?

Start with the plainest problem: elapsed enforcement time. China’s algorithm-filing regime has run since March 2022 — more than four years of registrations, security assessments and enforcement activity. The EU’s high-risk tier, the part of its Act closest in spirit to a general risk-based licence, will not bind most Annex III systems until December 2027 at the earliest [ 3 ] . The UK’s five principles have applied, non-statutorily, since 2023, but a regulator applying a principle it was already free to apply under its existing powers is a different claim from enforcing a new statute. Comparing outcomes today would mean comparing a system with years of live administrative data against one with close to zero years of its central mechanism’s operation, whose independent contribution is hard to isolate from what regulators were doing anyway. Effectiveness is only meaningful once the thing measured has run long enough, under comparable conditions, to produce an outcome — informally, $E_i \approx f(\text{coverage}_i,\ \text{enforcement}_i,\ t_i), \qquad t_i \ll t_j \text{ for several pairs } (i, j)$. where $t_i$ is time-in-force for approach i . When $t_i$ differs by an order of magnitude or more across the set compared, as it does here, no amount of careful measurement of coverage or enforcement intensity fixes the fact that the outcome variable has not had time to be generated for every entrant. This is why no figure in this article, or elsewhere in this publication, ranks these regimes by effectiveness.