Skip to content

Statistical Inference and Error Budgets

Lattice inference begins with correlated histories and ends with a claim assembled from many shared inputs. Between them lie equilibration choices, autocorrelation windows, nonlinear estimators, covariance matrices, spectral and continuum fits, scale setting, operator renormalization, model alternatives, and reproducibility checks. Treating any one stage as independent can understate uncertainty or count it twice; Sokal 1997, pp. 131–192 develops the correlation-aware Monte Carlo foundation, while Wolff 2004, pp. 143–153 gives a practical autocorrelation-error method.

Symptom or questionStart hereEvidence required
Error bars assume independent configurationsAutocorrelation times and effective sample sizeObservable-specific window, tail, and replica checks
Ratios, scales, or channels share dataEstimators, covariance, and resamplingCorrect resampling unit and joint covariance propagation
Fit changes with window or covariance treatmentCorrelated fits, model selection, and stability testsResidual, holdout, alternative-model, and synthetic-closure tests
Burn-in or late drift is uncertainEquilibration, stationarity, and chain diagnosticsMultiple starts, slow observables, distributions, and independent streams
Analyst choices may depend on the resultBlinding and independent reproductionFrozen decisions, controlled unblinding, alternative analysis
Scale, ZZ factors, and continuum fits are coupledMulti-stage correlated uncertaintyDependency graph or nested/joint propagation
A final precision claim is neededComplete lattice error budgetsSource, estimator, covariance, validation, and residual risk for every component

Correct transition-kernel construction belongs to the sampling chapter. This chapter starts with realized histories and asks whether the requested estimand and uncertainty are supported by those histories and the full downstream analysis.

Three statistical objects that must not be conflated

Section titled “Three statistical objects that must not be conflated”

For an observable history XtX_t:

  • the target distribution describes equilibrium variation of XX;
  • the transition kernel determines serial dependence and equilibration;
  • the analysis map turns the correlated history and auxiliary inputs into a final estimator.

A kernel can have the correct invariant distribution but mix too slowly for a finite run. A stationary run can be analyzed with the wrong covariance. A statistically impeccable finite-ensemble estimate can still lack continuum, volume, or operator control.

The shared dependency graph follows these layers from immutable ensemble identity to the final claim. Dashed arrows mark shared inputs or tests whose correlations cannot be discarded.

  1. Preserve configuration order, stream identity, update units, rejected states, thermalization history, and all analysis inputs.
  2. Predefine or justify the thermalization cut using multiple starts and slow observables.
  3. Estimate autocorrelation for each material observable and derived direction, not only for a plaquette-like monitor.
  4. Choose blocks, replicas, or nested resamples that preserve dependence through the entire nonlinear pipeline; Efron and Tibshirani 1993 supplies the general resampling framework.
  5. Fit with the full justified covariance, inspect whitened residuals and identifiability, and vary windows and plausible models.
  6. Propagate common scales, renormalization factors, tuning data, and interpolation inputs jointly.
  7. Test closure and coverage on synthetic or exact fixtures; perform a held-out or independent analysis.
  8. Assemble a claim-level uncertainty whose categories are mutually exclusive enough to avoid double counting.
ComponentRequired recordTypical negative control
Ensemble identityaction, parameters, volume, stream, update count, seed lineageswapped or duplicated configurations
Stationaritycut rule, starts, drift tests, slow observablesinjected exponential burn-in or late mean shift
Correlationρ(t)\rho(t), window, tail model, τint\tau_{\mathrm{int}}, uncertaintyAR(1) chain with known τint\tau_{\mathrm{int}}
Resamplingunit, block length, replicas, nesting, transform ordertreating correlated measurements as independent
Fitdata vector, covariance, conditioning, model, priors if any, windowhidden second state or rank-deficient covariance
Shared inputsscale, ZZ, tuning, common ensembles, covariance handoffindependently resampling a shared factor
Alternativesdeclared model and analysis variationschoose only the alternative nearest the preferred value
Final claimcomponent estimates, combination rule, correlations, validationadd one systematic twice or omit a slow tail

A small statistical error does not compensate for failed stationarity, coverage, operator matching, or continuum control. Conversely, a conservative-looking total error is not defensible if its components have no estimator or are combined with unknown correlation. Every material component should state how it was estimated, propagated, validated, and bounded when not directly identifiable.

  • Efron, B., and Tibshirani, R. J. (1993). An Introduction to the Bootstrap. Chapman & Hall/CRC. DOI.
  • Sokal, A. D. (1997). Monte Carlo methods in statistical mechanics: foundations and new algorithms. In C. DeWitt-Morette, P. Cartier, and A. Folacci (eds.), Functional Integration: Basics and Applications, pp. 131–192. Springer New York. DOI.
  • Wolff, U. (2004). Monte Carlo errors with less errors. Computer Physics Communications, 156, 143–153. DOI.