Statistics for comparing results
Compare two models, two prompts or two harness setups with statistics that hold up: calibration, conformal intervals, confidence sequences, covariance shrinkage and kernel two-sample tests.
15 shown here, each at the exact version the library release of October 9, 2026 serves.
What to watch for
- A point estimate without an interval cannot say whether two runs differ.
- Checking a running experiment again and again inflates false positives unless the interval is anytime-valid.
- With many features and few rows a sample covariance is unstable, so shrink it before you invert it.
Components
Brier score decomposition and expected calibration error
brier_decomposition_calibration_errorSplit the Brier score of probability forecasts into reliability, resolution, uncertainty and the two within-bin terms that make the decomposition exact for binned forecasts, and compute the expected calibration error.
- Runs with
- Python 3.10 or later
- Entry points
- brier_decomposition, expected_calibration_error
Split conformal prediction intervals
split_conformal_intervalsTurn any point predictor into prediction intervals with a finite-sample coverage guarantee, using held-out calibration residuals and the exact ceil((n + 1)(1 - alpha)) quantile index, optionally per group (Mondrian), with a seeded coverage check on held-out data.
- Runs with
- Python 3.10 or later
- Entry points
- conformal_quantile, split_conformal, coverage, coverage_simulation
Anytime-valid confidence sequence for a bounded mean
anytime_confidence_sequenceGive confidence intervals for the mean of bounded observations that hold at every time simultaneously, so results can be monitored after each run and stopped at any point.
- Runs with
- Python 3.10 or later
- Entry points
- hoeffding_sequence, betting_sequence, pointwise_wilson_sequence, coverage_simulation
Probabilistic and deflated Sharpe ratio
deflated_sharpe_ratioCompute the probability that a strategy's true Sharpe ratio exceeds a benchmark given skewness, kurtosis and sample length, and deflate it for having picked the best of many trials by comparing against the expected maximum Sharpe ratio of pure-luck trials.
- Runs with
- Python 3.10 or later
- Entry points
- sharpe_moments, probabilistic_sharpe_ratio, expected_maximum_sharpe, expected_maximum_of_normals, deflated_sharpe_ratio
Ledoit-Wolf covariance shrinkage
ledoit_wolf_shrinkageShrink a sample covariance toward a scaled identity with the Ledoit-Wolf intensity, giving a well-conditioned, positive definite estimate even when there are fewer observations than variables.
- Runs with
- Python 3.10 or later
- Entry points
- ledoit_wolf, shrink
Maximum mean discrepancy with an RBF kernel
rbf_maximum_mean_discrepancyCompare two samples of vectors with the kernel maximum mean discrepancy: biased and unbiased estimators of MMD squared under a Gaussian kernel, the median-distance bandwidth, and a seeded permutation test.
- Runs with
- Python 3.10 or later
- Entry points
- mmd_squared, permutation_test, median_bandwidth
Weighted Vendi score
weighted_vendi_scoreMeasure the effective number of distinct members in a weighted set from a similarity matrix or feature rows.
- Runs with
- Python 3.10 or later
- Entry points
- weighted_vendi_score, vendi_from_features
Effective rank, participation ratio and stable rank
effective_rank_spectral_entropyMeasure how many directions a representation matrix actually uses: the effective rank (exponential of the entropy of normalized singular values), the participation ratio of the eigenvalues and the stable rank.
- Runs with
- Python 3.10 or later
- Entry points
- spectral_dimensions, singular_values
Multicalibration audit by prediction bin and group
multicalibration_auditReport the mean residual (outcome minus prediction) in every prediction bin for every declared group and for the whole population, flag cells beyond a tolerance, and repair violations by iterative patching.
- Runs with
- Python 3.10 or later
- Entry points
- multicalibration_audit, multicalibrate
Within-group and between-group covariance decomposition
correlation_source_decompositionSplit the covariance between a score Y and a prediction P into the expected within-group covariance and the covariance of group means, exactly, using rational arithmetic.
- Runs with
- Python 3.10 or later
- Entry points
- decompose_covariance, decompose_variance
Covariance intersection fusion
covariance_intersection_fusionFuse two mean and covariance estimates whose errors may be correlated in an unknown way, choosing the weight that minimizes the trace or determinant of the fused covariance.
- Runs with
- Python 3.10 or later
- Entry points
- covariance_intersection, independent_fusion, conservative_margin
Dithered sign expectation and its inverse
dithered_sign_expectationCompute the mean of sign(x + noise) for Gaussian or uniform dither, 2 Phi(x/sigma) - 1 or x/a, check it against a seeded Monte Carlo estimate with its standard error, and invert it to recover x from an observed mean of one-bit readings.
- Runs with
- Python 3.10 or later
- Entry points
- sign_expectation, monte_carlo_sign_expectation, recover_offset
Transient amplification profile of a linear update
transient_amplification_profileCompute ||A^h||_2 over a horizon for a linear update x_(h+1) = A x_h, with the peak, the step after which the norm stays below 1, the spectral radius and the Gelfand bound.
- Runs with
- Python 3.10 or later
- Entry points
- transient_profile, spectral_norm, spectral_radius
Hodge decomposition of edge flows
hodge_edge_flow_decompositionSplit a flow on the edges of a small graph (pairwise preferences, score differences, transfers) into a gradient explained by a global potential, curl circulating around filled triangles, and harmonic circulation around holes.
- Runs with
- Python 3.10 or later
- Entry points
- hodge_decomposition, flow_from_potential
Delta-rule associative memory
delta_rule_associative_memoryStore key-value pairs in a matrix with the error-correcting update M <- M + rate (v - M k) k^T, retrieve with M k, and compare with the Hebbian rule and the minimum-norm memory.
- Runs with
- Python 3.10 or later
- Entry points
- delta_update, hebbian_update, retrieve, store_pairs, least_squares_memory
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