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Probability, statistics, inference, and uncertainty

Use this catalog when probability models, sampling, estimation, statistical evidence, prediction, measurement error, or uncertainty communication determine the answer. It is the canonical owner for general statistical reasoning. Domain catalogs should link here for the generic method and retain only the domain-specific design, authority, outcome, and validation constraints.

Contents

  1. Ownership boundary and routing
  2. Probability and stochastic models
  3. Sampling and study design
  4. Description, estimation, and uncertainty
  5. Testing and decision thresholds
  6. Regression, hierarchical, and multivariate models
  7. Time, event, and reliability data
  8. Bayesian inference and probabilistic prediction
  9. Missingness, measurement, and robustness
  10. Validation and communication
  11. Composition patterns
  12. Research anchors

Ownership boundary and routing

This catalog owns generic statistical procedures and their assumptions. Route a request here when the main question is how to represent variation, draw a sample, estimate a quantity, test a claim, predict an outcome, or quantify uncertainty.

Keep the domain catalog as the primary owner when the domain changes the governing decision or validity boundary:

  • causal identification and treatment effects remain in 08-decision-optimization-causality.md;
  • evidence-search and synthesis protocols remain in 31-research-evidence-investigation.md;
  • clinical-guideline appraisal and medical-device evidence remain in 35-human-factors-health-medical-devices.md;
  • spatial estimands and spatial dependence remain in 33-geospatial-location-analysis.md;
  • process control and manufacturing capability remain in 03-process-operations-quality.md and 14-physical-engineering-manufacturing.md;
  • reliability-specific models and maintenance decisions remain in 06-testing-reliability-safety-security.md and 34-asset-maintenance-reliability.md;
  • learning assessment and transfer remain in 18-learning-training-education.md.

The generic statistical method is linked rather than copied. Create a domain specialization only when it changes the experimental unit, sampling frame, estimand, authority, measurement system, or failure modes.

Probability and stochastic models

Candidate Type and output Use when Avoid when
Probability model mathematical representation uncertain states, events, or outcomes need explicit assumptions assign precise probabilities without a defensible reference class or elicitation process
Conditional probability and Bayes' rule probabilistic reasoning technique evidence changes the plausibility of hypotheses or events confuse P(A|B) with P(B|A) or omit base rates
Random variables and distributions probability model family variation, tail behavior, and dependence need a generative description fit a familiar distribution without checking support, tails, or dependence
Joint, marginal, and conditional distributions dependence representation multiple uncertain quantities interact or information arrives sequentially assume independence because the model is easier
Markov chains and state-space models stochastic process family future state depends on current state and transitions are meaningful collapse long memory, seasonality, or hidden state without testing the assumption
Poisson processes and counting models event-arrival model family events occur over exposure, time, or space and rates are meaningful ignore overdispersion, clustering, censoring, or changing exposure
Monte Carlo simulation uncertainty propagation technique a computational model can propagate input distributions and dependencies into outcome ranges structural model error dominates or input distributions are invented

Sampling and study design

Candidate Type and output Use when Avoid when
Target population and estimand definition study-framing method the quantity, population, time, and decision must be explicit before analysis treat an available dataset as if it automatically defines the target
Probability sampling sampling design family inclusion probabilities and population-level estimation matter claim population coverage from convenience or volunteer samples
Stratified sampling sampling design important subgroups differ or require precision/representation strata are poorly defined or allocation is unrelated to the decision
Cluster and multistage sampling sampling design units are naturally grouped, dispersed, or expensive to enumerate individually analyze clustered observations as independent without design correction
Survey weighting and calibration estimation adjustment unequal inclusion, nonresponse, or known population margins affect representation weights are treated as a cure for unmeasured selection bias
Randomized experiment causal study design assignment can be randomized and the intervention/outcome are measurable interference, noncompliance, rare harms, or inadequate power invalidate the design; see 08
Factorial and blocked design experimental design several factors, interactions, or nuisance gradients need efficient controlled comparison cells are too small or treatment assumptions are not stable
Quasi-experimental design causal design family randomization is unavailable but a credible assignment rule or comparison exists call adjustment alone causal without identification assumptions; see 08
Power and sample-size analysis design planning method detectable effect, precision, error rates, or resource limits must be made explicit use a conventional threshold without specifying estimand, variance, attrition, or practical importance

Description, estimation, and uncertainty

Candidate Type and output Use when Avoid when
Exploratory data analysis discovery/diagnostic method distributions, outliers, missingness, transformations, and relationships need inspection use exploratory patterns as confirmatory evidence without a new analysis plan
Robust summaries descriptive technique family skew, outliers, or heavy tails make mean/standard deviation fragile hide important tail behavior behind resistant summaries
Sampling distribution and standard error inferential concept repeated-sample variation of an estimator needs quantification mistake standard error for individual prediction uncertainty
Confidence interval frequentist interval procedure repeated-sampling coverage is the intended interpretation describe it as the probability that this fixed parameter lies in this interval
Prediction interval uncertainty interval a future individual or aggregate outcome needs a range use a confidence interval when outcome-level variation matters
Bootstrap resampling inference method analytic uncertainty is difficult and the data reasonably represent the sampling process small, dependent, censored, or boundary data violate the resampling design
Jackknife leave-one-out resampling method influence, bias, or variance can be approximated by deleting observations highly nonlinear or small-sample behavior makes the approximation unstable
Robust estimation estimation family contamination, heavy tails, or bounded influence are material select a robust estimator without explaining the target estimand
Measurement uncertainty budget uncertainty-analysis method instruments, processes, and inputs contribute identifiable uncertainty components report a single error bar without traceable components or calibration context

Testing and decision thresholds

Candidate Type and output Use when Avoid when
Null and alternative hypotheses inferential framing a claim needs a specified reference model and departure of interest use a null merely because software requires one
Permutation test randomization-based test exchangeability or a valid assignment mechanism supports the reference distribution permute observations that are clustered, dependent, or structurally different
Randomization inference design-based inference treatment assignment itself defines the exact reference distribution assignment was not randomized or the estimand is left implicit
Likelihood-ratio test model comparison test nested models and likelihood assumptions are credible use asymptotic thresholds with sparse, boundary, or weakly identified models without checks
Multiple-comparisons control error-control family many hypotheses or searches increase false-discovery risk suppress exploration or treat adjusted significance as practical importance
False discovery rate control error-control method many findings are screened and a controlled discovery proportion is useful confirmatory safety or legal gates require familywise or deterministic evidence
Equivalence and non-inferiority testing decision test acceptable difference bounds are defined before comparison declare equivalence from a non-significant difference
Sequential analysis adaptive inference design data arrive over time and stopping rules must preserve error properties repeatedly inspect fixed-horizon tests without a valid sequential design
Calibration analysis probabilistic-quality assessment predicted probabilities must match observed frequencies use discrimination alone as evidence of reliable probabilities

Regression, hierarchical, and multivariate models

Candidate Type and output Use when Avoid when
Linear regression conditional-mean model a continuous outcome and additive effects are adequate approximations extrapolate beyond support or treat association as causation
Generalized linear model regression model family binary, count, rate, or non-Gaussian outcomes need a link and mean-variance model ignore separation, overdispersion, zero inflation, or exposure offsets
Generalized additive model flexible regression model smooth nonlinear relationships are plausible and interpretable partial effects are useful tune smoothness until a desired story appears
Mixed-effects model hierarchical regression observations are nested, repeated, or grouped with partial pooling ignore the grouping process or treat random effects as automatic causal correction
Bayesian hierarchical model probabilistic multilevel model sparse groups, prior knowledge, and full posterior uncertainty are valuable priors are hidden, untested, or used to overwhelm contradictory data
Quantile regression distributional regression effects differ across the outcome distribution or tails matter interpret quantile effects as mean effects
Principal component analysis dimension-reduction technique correlated variables need a lower-dimensional representation for exploration or modeling components are treated as discovered constructs without interpretation or stability checks
Cluster analysis unsupervised grouping family similarity-based segmentation is exploratory and downstream action is defined clusters are treated as natural categories or validated outcomes without stability evidence

Time, event, and reliability data

Candidate Type and output Use when Avoid when
Time-series decomposition temporal diagnostic trend, seasonality, cycles, and residual variation must be separated infer causal effects from decomposed patterns alone
ARIMA/ETS forecasting forecasting model family serial dependence and forecast horizons are reasonably stable structural breaks, interventions, or regime changes are ignored
State-space and Kalman filtering dynamic estimation method latent state evolves over time and noisy observations arrive sequentially linear/Gaussian assumptions are materially false without a suitable extension
Survival analysis time-to-event method family censoring, event timing, and hazard are central censoring is informative but treated as independent
Kaplan–Meier estimator nonparametric survival estimator survival curves need transparent group description under right censoring competing risks or time-varying exposures are ignored
Cox proportional-hazards model semiparametric survival model hazard ratios are useful and proportionality is defensible proportional hazards fail and no time-varying or alternative model is considered
Competing-risks analysis event-history method multiple mutually exclusive event types alter the risk set cumulative incidence is replaced by an incompatible survival interpretation

Bayesian inference and probabilistic prediction

Candidate Type and output Use when Avoid when
Bayesian model specification inferential framework priors, likelihood, posterior, and predictive quantities can be made explicit use a prior as an unreviewed value judgment or hide sensitivity
Posterior predictive checking model criticism method simulated outcomes should be compared with relevant observed features check only average fit and ignore failures important to the decision
Bayesian model comparison predictive/model-selection family competing models and uncertainty about model structure matter interpret a selected model as true or ignore prior/model sensitivity
Probabilistic forecasting prediction method decisions depend on calibrated distributions rather than point forecasts reward sharpness without calibration or penalize honest uncertainty
Conformal prediction distribution-free predictive inference family finite-sample marginal coverage is useful under exchangeability claim conditional coverage under drift, dependence, or distribution shift without evidence

Missingness, measurement, and robustness

Candidate Type and output Use when Avoid when
Missing-data mechanism analysis diagnostic/framing method MCAR, MAR, MNAR assumptions affect what can be learned label missingness from the pattern alone without process knowledge
Multiple imputation missing-data method uncertainty from incomplete observations can be modeled under defensible assumptions fill values once and treat them as observed data
Sensitivity analysis for missingness robustness method conclusions may change under departures from the primary missingness model present one arbitrary scenario as a bound
Measurement invariance measurement-validation method scores must be compared across groups, times, or contexts assume the same instrument has the same meaning everywhere
Inter-rater reliability measurement agreement family human judgments or coding require consistency assessment agreement is treated as validity or disagreement is removed silently
Error-in-variables analysis measurement-error method predictors are measured with material error regress noisy proxies as if they were exact causes
Influence and outlier diagnostics model-criticism technique individual observations can materially alter estimates or decisions delete inconvenient observations without a predeclared rule and explanation
Robustness and sensitivity analysis uncertainty-assurance family reasonable analytic choices could change the conclusion run a large undisclosed garden of analyses and report only favorable ones

Validation and communication

Candidate Type and output Use when Avoid when
Simulation-based calibration Bayesian computation diagnostic posterior computation and inferential recovery need testing on known simulated data treat computational agreement as substantive model validation
Cross-validation predictive validation family out-of-sample prediction or model comparison is the target use random folds with leakage, temporal dependence, or grouped data
Nested cross-validation tuning/evaluation design model selection and performance estimation must be separated data are too scarce for stable outer estimates without reporting uncertainty
Temporal or group-aware validation validation design deployment predicts future periods or new groups/sites random split leaks information across the deployment boundary
External validation transportability check a model or estimate must work in a new population, site, period, or system call a held-out split from the same source external validation
Reproducible analysis evidence practice code, data transformations, environments, and decisions should be rerun and inspected assume a notebook alone proves provenance or correctness
Statistical reporting checklist communication assurance analysis decisions, estimands, uncertainty, missingness, and limitations must be reviewable use reporting compliance as a substitute for sound design

Composition patterns

Estimate a population quantity

target population + estimand → sampling frame/design → measurement validation → weighted/adjusted estimator → uncertainty interval → sensitivity to nonresponse/missingness → decision interpretation

Compare an intervention

causal question → estimand → randomized or quasi-experimental design → power/precision → pre-specified analysis → effect estimate + uncertainty → diagnostics/refutations → practical and distributional interpretation

Build a predictive model

deployment decision → target and prediction horizon → leakage-safe split → baseline → model family → calibration + discrimination/error → subgroup and shift checks → external/temporal validation → monitoring and recalibration

Analyze a small, messy dataset

data-generating process → provenance and measurement audit → exploratory analysis → missingness/outlier diagnosis → robust/simple model → sensitivity analysis → cautious inference or decision rule

Do not use a p-value, confidence interval, model score, or posterior as a substitute for a clear estimand, valid design, measurement quality, or decision relevance.

Research anchors