Algorithm Lab

Verified statistical algorithms with formulas, assumptions and references. Every algorithm is validated against Minitab, R, or NIST reference data.

Distributions & Tests

Process Capability

Hypothesis Tests

Shapiro-Wilk Test
Tests whether a sample comes from a normally distributed population.
Anderson-Darling Test
Tests whether a sample comes from a normally distributed population — especially sensitive in the distribution tails.
Jarque-Bera Test
Asymptotic normality test based on skewness and kurtosis (chi-squared with 2 degrees of freedom). Reliable for large samples (n > 30).
D'Agostino-Pearson Omnibus Test
Omnibus normality test: Combines Z-scores from skewness and kurtosis into a χ²(2) test statistic. Requires n ≥ 20.
Chi-Square Variance Test
Tests whether the population variance equals a hypothesized value (one-sample variance test).
F-Test (Variance Equality)
Tests whether two normally distributed populations have equal variances.
Levene Test (Brown-Forsythe)
Robust test for equality of variances of two samples, insensitive to non-normality.
One-Sample t-Test
Tests whether the population mean equals a hypothesized value.
Two-Sample t-Test (pooled)
Compares the means of two independent samples assuming equal variances.
Welch t-Test
Compares the means of two independent samples without assuming equal variances.
Wilcoxon Signed-Rank Test
Nonparametric alternative to the one-sample t-test for the median.
Mann-Whitney U Test
Nonparametric alternative to the two-sample t-test for independent samples.
One-Way ANOVA
Compares the means of k independent, normally distributed samples.
Kruskal-Wallis Test
Nonparametric alternative to one-way ANOVA for k samples.
Bartlett's Test
Parametric test for equality of variances of k ≥ 2 normally distributed samples.

Outlier Tests

Regression & Correlation

Regression ANOVA (Variance Decomposition)
Decomposes total variation of the response into explained (regression) and unexplained (residual) components.
Regression Coefficients (t-Test & Confidence Intervals)
Tests the significance of individual regression coefficients via t-test and determines confidence intervals.
Correlation Analysis (Pearson, Spearman, Kendall)
Computes Pearson r, Spearman ρ and Kendall τ including p-values and confidence intervals.
Logistic Regression (Binomial GLM)
Models a binary response (0/1) as a function of predictors using the logistic link function and IRLS estimation.
Poisson Regression
Generalized linear model for count data with log link function and Poisson distribution.
Negative Binomial Regression
Regression model for overdispersed count data using a log link and negative binomial distribution.
ROC Curve & AUC
Computes the ROC curve (Receiver Operating Characteristic) and the Area Under the Curve (AUC) for binary classification.
Hosmer-Lemeshow Test
Tests the goodness of fit of a logistic regression model using groups of predicted probabilities.
Overdispersion Check
Checks for overdispersion in count data models using the Pearson χ²/df ratio.
Lack-of-Fit Test (F-Test from Replicate Observations)
Compares model mis-specification against pure noise from replicated design points.
Effect Coding (Sum-to-Zero) for Categorical Factors
Maps a categorical factor with k levels onto k − 1 indicator columns; the intercept becomes the grand mean.
Block-Significance F-Test (Type-III SS for a Factor Block)
Wald-form F-test for a group of related model-matrix columns — typically the n − 1 indicators that encode one categorical factor.

Measurement System Analysis

Control Charts

Design of Experiments

Response Optimization