References
Every tool here maps to a real-world use and to public, citable authority. This page is that mapping — the software, where it is used, and the references: the companion Solved By Stats explainer plus the primary sources each method is anchored to. SWS does; SBS explains.
| Software | Where it is used | References |
|---|---|---|
| Confidence Interval Calculator Estimation | Putting an honest range around a sample estimate: A/B-test and conversion-rate ranges, manufacturing tolerances and quality control, polling and survey margins of error, clinical effect ranges, and engineering measurement and reliability uncertainty. | Explainer: Confidence Intervals: Putting an Honest Range Around an Estimate
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| Welch's Two-Sample t-test Hypothesis testingnew | Comparing two groups whose sizes or variances differ: A/B tests with unequal samples, two production lines or machines or materials, treatment versus control in experiments, campaign-versus-campaign in marketing, player- or team-comparison in sports analytics, and treatment-outcome comparisons. | Explainers: Hypothesis Testing: A Step-by-Step Guide · What a p-value Actually Tells You
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Every tool ships paired with a plain-language explainer on Solved By Stats — the tool computes, the explainer teaches the idea. New tools (probability, graph theory, geometry) land the same way, each added to this map.
Citation canon
SWS builds its math from first principles and anchors both method and numerical correctness to public authority. A source is cited only if its URL returns HTTP 200; gated or paywalled material is background only.
- Methods: NIST/SEMATECH e-Handbook of Statistical Methods, American Statistical Association.
- Numerical correctness: NIST Statistical Reference Datasets (StRD) — certified values the in-browser self-test checks against (see Software & sources). Distribution and inference cross-checks are pinned from SciPy and statsmodels.
- Applied & educational canon: Our World in Data, scikit-learn, Penn State STAT, Statistics LibreTexts, Australian Bureau of Statistics.
Live numerical verification runs on the Software & sources page.