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m-bias errors: leave-one-tile-out jackknife; drop the cumulative file #346

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@cailmdaley

ImageSimMBias computes m/c on the full pooled sample with a paired object bootstrap. Object resampling assumes galaxies are independent, but tile-level systematics (PSF model, background, selection) correlate objects within a tile, so the bootstrap can underestimate the error.

  • Carry a tile id per object through the extracted cut catalogue (patch name from final_cat_*.hdf5).
  • Add a leave-one-tile-out jackknife for m/c errors, reported alongside the bootstrap; disagreement between the two is itself a tile-systematics diagnostic.
  • Replace mbias_cumulative.yaml / plot_convergence (stateful across runs, mixes code versions) with an in-run convergence curve: m on the first k tiles, k=1..N, jackknife errors.

Raised by Fabian (Slack, 2026-09-14); he'd read the cumulative plot as per-tile averaging — the estimator is already full-sample.

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