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HarrypatriaHarrypatria/data-mining-ml/skills/statistical-analysis/SKILL.md

statistical-analysis

Skill2 starsChanged 12 days agoMITView on GitHub

Statistical Analysis. Hypothesis tests, A/B tests and experiments, confidence intervals, effect sizes, power and sample size, multiple comparisons, regression diagnostics, Bayesian alternatives, time series (stationarity, ARIMA, ETS) and survival analysis (Kaplan-Meier, Cox), with causal caution (randomization, difference-in-differences, matching, instrumental variables). Use for statistics, significance testing, t-test, chi-squared, ANOVA, Mann-Whitney, correlation, regression interpretation, experiment readouts, or any causal question.

46 other projects use a version of this.

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Projects with it also use evidence-driven-writing, experiment-results-planning and 10 more.

Other files people use alongside this one.

Files found in the same public projects as a version of this one, more often than they turn up anywhere else. Each project counts once, large collections count for less, and this file's own repository is left out.
  • Norman-burySkill

    evidence-driven-writing

    Use when writing or revising Introduction, Related Work, background, literature synthesis, or any section where references must drive claims

    Also in 3 projects that use this

  • Norman-burySkill

    experiment-results-planning

    Use when designing experiments, result tables, mock planning data, evaluation protocols, or results sections before real data are final

    Also in 3 projects that use this

  • +10 more from Norman-bury

The file

We split this skill into the rules it gives an agent

3 rules. 0 are common, 2 are distinctive, and 1 is very specific to this project.

  • 0

    Common

    Most of the 39 edited versions we read keep these.

  • 2

    Distinctive

    This author's own choices. Worth a look.

  • 1

    Very specific

    Tied to their project's names, files or tools. Probably skip.

  • Common
  • Distinctive
  • Very specific
  1. Very specific:

    Check independence, normality (Shapiro-Wilk with Q-Q plot, sample-size aware), equal variance (Levene), and sample size, then follow …

    line 20
  2. Distinctive:

    No peeking. If interim looks are needed, use a pre-registered sequential design (alpha spending).

    line 35
  3. Distinctive:

    Check sample ratio mismatch (chi-squared on assignment counts) before reading results.

    line 37

“Common” is measured: kept by at least 6 in 10 of the 39 edited versions of this file we could read. “Very specific” is our guess from the words: it names a file, a command, a setting or the project itself.

Keep what fits and drop the rest. Your version, ready for your agents.
Files
SKILL.md

Statistical Analysis

Explore first (Tukey), then infer. A bare p-value is a defect.

Before running any test, write

  1. Question in plain words.
  2. Estimand: the exact quantity (difference in means, ratio of proportions, hazard ratio).
  3. Null and alternative, one- or two-sided, and alpha.
  4. Design: randomized, observational, paired, clustered.
  5. Minimum effect worth acting on, and the power to detect it.

Choose the test from the data

Check independence, normality (Shapiro-Wilk with Q-Q plot, sample-size aware), equal variance (Levene), and sample size, then follow references/test-selection.md. Default to Welch's t-test over Student's. Use rank or exact tests when assumptions fail.

Report

AlwaysExample form
Effect sizedifference, Cohen's d, odds ratio, Cramer's V
Interval95 percent CI (analytical or bootstrap)
p-valueexact, with the test named
Sample sizesper group
CorrectionHolm or Benjamini-Hochberg when several tests

Experiments and A/B tests

  • Power analysis before launch (statsmodels.stats.power). Fix duration and sample size in advance.
  • No peeking. If interim looks are needed, use a pre-registered sequential design (alpha spending).
  • One primary metric; guardrails reported but not used to declare a win.
  • Check sample ratio mismatch (chi-squared on assignment counts) before reading results.
  • Clustered randomization needs cluster-robust errors.

Causation

Correlation is not causation. A causal claim needs a design: randomization, difference-in-differences (parallel trends), matching or weighting (no unmeasured confounding), instrumental variables (exclusion restriction), regression discontinuity. List the untestable assumptions. Without a design, write "is associated with".

Regression

Diagnostics before reading coefficients: residual plots, VIF, influence (Cook's distance), Breusch-Pagan, Q-Q plot. Use robust (HC3) standard errors when heteroscedastic.

Bayesian alternative

Offer it for small samples or when priors matter: Beta-Binomial for conversion rates, normal models with weakly informative priors; report posterior intervals and the probability the effect exceeds the minimum meaningful effect.

Time series and survival

Stationarity (ADF, KPSS), decomposition, ARIMA or ETS with residual diagnostics, forward-chaining validation; Kaplan-Meier, log-rank, Cox with proportional-hazards checks, censoring explained. references/time-series-survival.md.

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