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How many bootstrap resamples do you need, and which statistics does it handle?

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Answer

  • Given data X1X_{1},...,XnX_{n}, sample n observations with replacement to form X*, compute the statistic θ̂*, repeat B ≈ 1000-10000 times to build an empirical distribution of θ̂.
  • Use it to compute SEs, CIs, and bias.
  • Works for any statistic (median,  quantiles,  R2,  ratios)(\mathrm{median}, \;\mathrm{quantiles}, \;R^{2}, \;\mathrm{ratios}), no distributional assumption.
  • Weaknesses: bad for extreme statistics (max), heavy tails, small n, and violated i.i.d.
Check yourself — multiple choice
  • Cross-validation
  • Resample n with replacement B times → empirical distribution of θ̂ → SE / CI / bias; distribution-free but bad for max / heavy tails / tiny n
  • Same as t-test
  • Only parametric

Bootstrap: resample with replacement; empirical θ̂ distribution; distribution-free.

#bootstrap#confidence-interval#non-parametric

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