Latest Statistical Tests Articles

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Diagram showing a sample cumulative distribution curve compared against a theoretical normal curve, with the tail regions highlighted to illustrate the extra weighting used by the Anderson-Darling Test.
Article · July 2026

Anderson-Darling Test

A complete guide to the Anderson-Darling Test-formula, hypotheses, assumptions, hand-worked numerical examples, critical-value interpretation, tail sensitivity, and a scipy Python walkthrough for testing goodness-of-fit against a normal distribution.

Article · July 2026

Augmented Dickey-Fuller Test

A complete guide to the Augmented Dickey-Fuller (ADF) Test-formula, hypotheses, assumptions, hand-worked numerical examples, critical values, and a statsmodels.tsa.stattools.adfuller Python walkthrough for testing stationarity in time series data.

Diagram of several bell-shaped normal distributions with different widths side by side, illustrating the unequal variances across groups that Bartlett's Test is designed to detect.
Article · July 2026

Bartlett's Test

A complete guide to Bartlett's Test-formula, hypotheses, assumptions, hand-worked numerical examples, the correction factor, and a scipy.stats.bartlett Python walkthrough for testing equality of variances across normally distributed groups.

Diagram showing a prior distribution over effect size being updated by observed data into a posterior distribution, with a Bayes factor comparing evidence for the null and alternative hypotheses, illustrating the logic of a Bayesian t-test.
Article · July 2026

Bayesian t-test

A complete guide to the Bayesian t-test-priors, posteriors, the Bayes factor, credible intervals, hand-worked numerical intuition, and a Python walkthrough using pingouin and PyMC.

Diagram of a residuals-versus-fitted-values scatterplot showing a funnel-shaped spread that widens as fitted values increase, illustrating the heteroskedasticity the Breusch-Pagan Test is designed to detect.
Article · July 2026

Breusch-Pagan Test

A complete guide to the Breusch-Pagan Test-formula, hypotheses, assumptions, hand-worked numerical examples, the Koenker studentized version, and a statsmodels.stats.diagnostic.het_breuschpagan Python walkthrough for detecting heteroskedasticity in regression residuals.

Diagram of several box plots with median lines and different spreads side by side, illustrating the median-centered deviations that the Brown-Forsythe Test uses to detect unequal variances across groups.
Article · July 2026

Brown-Forsythe Test

A complete guide to the Brown-Forsythe Test-formula, hypotheses, assumptions, hand-worked numerical examples, its two related meanings (equal-variance test and unequal-variances ANOVA F* test), and a scipy.stats Python walkthrough.

Diagram of a contingency table with rows and columns representing two categorical variables, showing observed cell counts next to expected cell counts, illustrating how the Chi-Square Test of Independence detects an association between categorical variables.
Article · July 2026

Chi-Square Test of Independence

A complete guide to the Chi-Square Test of Independence-formula, hypotheses, assumptions, hand-worked numerical examples, Cramer's V effect size, and a scipy.stats.chi2_contingency Python walkthrough for categorical data.

Diagram of a subjects-by-conditions binary data matrix with success and failure marks across three or more related conditions, illustrating how Cochran's Q Test detects whether the proportion of successes differs across conditions for the same subjects.
Article · July 2026

Cochran's Q Test

A complete guide to Cochran's Q Test-formula, hypotheses, assumptions, hand-worked numerical examples, post-hoc pairwise McNemar comparisons, effect size, and a statsmodels.stats.contingency_tables.cochrans_q Python walkthrough for repeated binary measures.

Diagram of several repeated random train/test splits of the same dataset, each producing a performance difference between two classifiers, with a variance correction term highlighted, illustrating how the corrected resampled t-test adjusts for overlapping training sets across repetitions.
Article · July 2026

Corrected Resampled t-test

A complete guide to the Corrected Resampled t-test (Nadeau and Bengio's test)-formula, hypotheses, assumptions, hand-worked numerical examples, why the ordinary paired t-test underestimates variance across repeated random train/test splits, and a from-scratch Python walkthrough for statistically comparing two machine learning models.

Diagram of two survival curves for different covariate groups with a constant hazard ratio between them over time, illustrating the proportional hazards assumption that the Cox model relies on.
Article · July 2026

Cox Proportional Hazards Test

A complete guide to the Cox Proportional Hazards Test-formula, hypotheses, assumptions, hand-worked numerical examples, hazard ratio interpretation, the proportional hazards assumption check, and a lifelines Python walkthrough for survival analysis.

Diagram showing a sample distribution curve alongside a normal curve, with skewness and kurtosis highlighted as the two components combined into the D'Agostino-Pearson omnibus K-squared statistic.
Article · July 2026

D'Agostino-Pearson Test

A complete guide to the D'Agostino-Pearson Test-formula, hypotheses, assumptions, hand-worked numerical examples, skewness and kurtosis interpretation, and a scipy Python walkthrough for testing normality using an omnibus K-squared statistic.

Diagram of two overlapping ROC curves evaluated on the same set of subjects, with their AUC values and a covariance term highlighted, illustrating how DeLong's Test compares correlated classifier performance.
Article · July 2026

DeLong's Test

A complete guide to DeLong's Test for comparing two correlated ROC AUCs-formula, hypotheses, assumptions, hand-worked numerical examples, the structural relationship to the Mann-Whitney U statistic, and a Python (roc_auc_score + delong-style covariance) walkthrough for paired classifier comparison.

Diagram showing mean ranks for three or more independent groups plotted on a number line with pairwise comparison brackets, illustrating how Dunn's Post-Hoc Test identifies which specific pairs of groups differ after a significant Kruskal-Wallis Test.
Article · July 2026

Dunn's Post-Hoc Test

A complete guide to Dunn's Post-Hoc Test-formula, hypotheses, assumptions, hand-worked numerical examples, p-value adjustment methods, and a scikit-posthocs Python walkthrough after a significant Kruskal-Wallis Test.

Diagram of a regression residual plot over time showing consecutive residuals trending together, illustrating the positive autocorrelation the Durbin-Watson Test is designed to detect.
Article · July 2026

Durbin-Watson Test

A complete guide to the Durbin-Watson Test-formula, hypotheses, assumptions, hand-worked numerical examples, the inconclusive zone, and a statsmodels.stats.stattools.durbin_watson Python walkthrough for detecting autocorrelation in regression residuals.

Diagram of two bell-shaped normal distributions with different widths side by side, illustrating the unequal variances across two groups that the F-Test for Equality of Variances is designed to detect.
Article · July 2026

F-Test for Equality of Variances

A complete guide to the F-Test for Equality of Variances-formula, hypotheses, assumptions, hand-worked numerical examples, one-tailed vs two-tailed usage, and a scipy.stats Python walkthrough for comparing the variances of two normally distributed groups.

Diagram of a 2x2 contingency table with fixed row and column totals, showing the set of all possible tables under the hypergeometric distribution, illustrating how Fisher's Exact Test computes an exact p-value for small-sample categorical data.
Article · July 2026

Fisher's Exact Test

A complete guide to Fisher's Exact Test-formula, hypotheses, assumptions, hand-worked numerical examples using the hypergeometric distribution, odds ratio effect size, one-sided vs two-sided tests, and a scipy.stats.fisher_exact Python walkthrough for small-sample categorical data.

Diagram showing the same subjects measured under three or more related conditions, with scores ranked within each subject row, illustrating how the Friedman Test detects systematic differences across repeated measurements without assuming normality.
Article · July 2026

Friedman Test

A complete guide to the Friedman Test-formula, hypotheses, assumptions, hand-worked numerical examples, effect size, Nemenyi post-hoc comparisons, and a scipy.stats.friedmanchisquare Python walkthrough.

Diagram of two time series where the lagged values of one series feed into a regression predicting the other, illustrating how the Granger Causality Test measures whether one series has predictive power over another.
Article · July 2026

Granger Causality Test

A complete guide to the Granger Causality Test-formula, hypotheses, assumptions, hand-worked numerical examples, the critical stationarity and lag-order steps, and a statsmodels.tsa.stattools.grangercausalitytests Python walkthrough for testing whether one time series helps predict another.

Diagram of a deciles-of-risk table showing observed and expected event counts across ten probability groups, illustrating how the Hosmer-Lemeshow Test evaluates logistic regression goodness-of-fit.
Article · July 2026

Hosmer-Lemeshow Test

A complete guide to the Hosmer-Lemeshow Test-formula, deciles-of-risk table construction, hand-worked numerical examples, degrees-of-freedom rules, and a Python (statsmodels-compatible) walkthrough for checking goodness-of-fit in logistic regression models.

Diagram showing two separate unrelated groups of subjects with distinct distributions, illustrating the between-group comparison analyzed by an independent samples t-test.
Article · July 2026

Independent Samples t-test

A complete guide to the independent samples t-test (two-sample t-test)-formula, hypotheses, assumptions, hand-worked numerical examples, effect size, Welch's correction, and a scipy.stats.ttest_ind Python walkthrough.

Diagram of two step-shaped empirical cumulative distribution function curves with the largest vertical gap between them highlighted, illustrating the D statistic used by the Kolmogorov-Smirnov Test.
Article · July 2026

Kolmogorov-Smirnov Test

A complete guide to the Kolmogorov-Smirnov Test-formula, hypotheses, assumptions, hand-worked one-sample and two-sample numerical examples, ECDF comparison, and a scipy Python walkthrough for testing goodness-of-fit and comparing distributions.

Article · August 2026

KPSS Test

A complete guide to the KPSS Test (Kwiatkowski-Phillips-Schmidt-Shin Test)-formula, hypotheses, assumptions, hand-worked numerical examples, critical values, and a statsmodels.tsa.stattools.kpss Python walkthrough for testing stationarity in time series data.

Diagram showing three or more independent groups of subjects with their combined observations ranked together, illustrating how the Kruskal-Wallis Test detects systematic differences across independent groups without assuming normality.
Article · July 2026

Kruskal-Wallis Test

A complete guide to the Kruskal-Wallis Test-formula, hypotheses, assumptions, hand-worked numerical examples, effect size, Dunn's post-hoc test, and a scipy.stats.kruskal Python walkthrough.

Diagram of several box plots with different spreads side by side, illustrating the unequal variances across groups that Levene's Test is designed to detect.
Article · July 2026

Levene's Test

A complete guide to Levene's Test-formula, hypotheses, assumptions, hand-worked numerical examples, the Brown-Forsythe modification, and a scipy.stats.levene Python walkthrough for testing equality of variances across groups.

Diagram of two nested statistical models-a restricted null model and a more flexible alternative model-fit to the same dataset, with their log-likelihoods and the resulting chi-square test statistic highlighted, illustrating how the Likelihood Ratio Test compares nested model fit.
Article · July 2026

Likelihood Ratio Test

A complete guide to the Likelihood Ratio Test for comparing nested statistical models-formula, hypotheses, assumptions, hand-worked numerical examples, Wilks' theorem, and a Python (statsmodels / scipy) walkthrough for comparing nested regression and generalized linear models.

Diagram comparing a sample's step-shaped empirical distribution function against a fitted normal cumulative curve, illustrating what the Lilliefors Test measures.
Article · July 2026

Lilliefors Test

A complete guide to the Lilliefors Test-formula, hypotheses, the corrected critical value table, hand-worked numerical examples, and a statsmodels Python walkthrough for testing normality when the mean and variance are estimated from the sample.

Article · July 2026

Ljung-Box Test

A complete guide to the Ljung-Box Test-formula, hypotheses, assumptions, hand-worked numerical examples, chi-square critical values, and a statsmodels.stats.diagnostic.acorr_ljungbox Python walkthrough for detecting autocorrelation across multiple lags in time series and residuals.

Diagram of two Kaplan-Meier survival curves for different groups diverging over time, illustrating the observed-versus-expected event comparison that the Log-Rank Test uses to detect a difference in survival.
Article · July 2026

Log-Rank Test

A complete guide to the Log-Rank Test-formula, hypotheses, assumptions, hand-worked numerical examples, Kaplan-Meier curve comparison, stratified and trend variants, and a lifelines Python walkthrough for comparing survival between groups.

Diagram showing two separate unrelated groups of subjects with their combined observations ranked together, illustrating the rank-sum comparison analyzed by a Mann-Whitney U Test.
Article · July 2026

Mann-Whitney U Test

A complete guide to the Mann-Whitney U Test (Wilcoxon Rank-Sum Test)-formula, hypotheses, assumptions, hand-worked numerical examples, effect size, and a scipy.stats.mannwhitneyu Python walkthrough.

Diagram of a 2x2 paired contingency table with before and after binary outcomes, highlighting the two discordant off-diagonal cells that McNemar's Test compares, illustrating how the test detects asymmetric change in matched-pair categorical data.
Article · July 2026

McNemar's Test

A complete guide to McNemar's Test-formula, hypotheses, assumptions, hand-worked numerical examples, continuity correction, exact binomial version, odds ratio effect size, and a statsmodels.stats.contingency_tables.mcnemar Python walkthrough for paired binary data.

Diagram of a staircase-like path through a 3D grid of input values, with arrows showing one input changing at each step and the resulting output jump, illustrating how the Morris Method builds elementary effects.
Article · July 2026

Morris Elementary Effects Method

A clear, practical guide to the Morris Elementary Effects Method-what it is, the mu-star and sigma statistics, a hand-worked numerical example you can check yourself, and a SALib Python walkthrough for quickly screening which model inputs actually matter.

Diagram showing average ranks for three or more related conditions plotted on a number line with a critical-difference bar, illustrating how the Nemenyi Post-Hoc Test identifies which specific pairs of conditions differ after a significant Friedman Test.
Article · July 2026

Nemenyi Post-Hoc Test

A complete guide to the Nemenyi Post-Hoc Test-formula, hypotheses, assumptions, hand-worked numerical examples, critical difference diagrams, and a scikit-posthocs Python walkthrough after a significant Friedman Test.

Diagram showing paired before-and-after measurements for the same subjects connected by lines, illustrating the within-subject differences analyzed by a paired t-test.
Article · July 2026

Paired t-test

A complete guide to the paired t-test (dependent t-test)-formula, hypotheses, assumptions, hand-worked numerical examples, effect size, and a scipy.stats.ttest_rel Python walkthrough.

Diagram showing observations from two groups being pooled and their group labels randomly reshuffled many times to build an empirical null distribution, illustrating the logic of a Permutation Test.
Article · July 2026

Permutation Test

A complete guide to the Permutation Test (randomization test)-core idea, when to use it, hand-worked numerical examples, relationship to the Mann-Whitney U Test and t-test, and a Python walkthrough using scipy.stats.permutation_test.

Diagram of a scatterplot with a curved true relationship and a straight regression line fitted through it, illustrating the functional-form misspecification the Ramsey RESET Test is designed to detect.
Article · July 2026

Ramsey RESET Test

A complete guide to the Ramsey RESET Test-formula, hypotheses, assumptions, hand-worked numerical examples, and a statsmodels.stats.diagnostic.linear_reset Python walkthrough for detecting omitted nonlinearity and functional-form misspecification in regression models.

Diagram of a log-likelihood curve showing the score (slope) evaluated at the null-hypothesis parameter value, illustrating how the Score Test uses only the restricted model fit.
Article · July 2026

Score Test (LM Test)

A complete guide to the Score Test (Lagrange Multiplier Test)-formula, intuition, relationship to the Wald and Likelihood Ratio tests, hand-worked numerical examples, and a Python (statsmodels/scipy) walkthrough.

Diagram contrasting a bell-shaped normal distribution with a skewed distribution, illustrating what the Shapiro-Wilk Test detects when checking a sample for normality.
Article · July 2026

Shapiro-Wilk Test

A complete guide to the Shapiro-Wilk Test-formula, hypotheses, assumptions, hand-worked numerical examples, Q-Q plot interpretation, and a scipy Python walkthrough for testing whether sample data comes from a normal distribution.

Diagram showing total output variance of an epidemic or engineering model being decomposed into first-order contributions from individual inputs and higher-order contributions from interactions between inputs, illustrating the logic of Sobol Sensitivity Analysis.
Article · July 2026

Sobol Sensitivity Analysis

A complete guide to Sobol Sensitivity Analysis-first-order and total-order indices, variance decomposition, hand-worked numerical intuition, and a Python walkthrough using SALib applied to an SIR epidemic model.

Diagram showing group means for three or more independent groups plotted on a number line with a Tukey HSD bar, illustrating how Tukey's Honest Significant Difference Test identifies which specific pairs of groups differ after a significant one-way ANOVA.
Article · July 2026

Tukey's HSD Test

A complete guide to Tukey's Honest Significant Difference (HSD) Test-formula, hypotheses, assumptions, hand-worked numerical examples, confidence intervals, and a statsmodels pairwise_tukeyhsd Python walkthrough.

Diagram of a fitted parameter estimate with its standard error and a hypothesized null value marked on a number line, with the standardized distance between them highlighted, illustrating how the Wald Test evaluates parameter significance.
Article · July 2026

Wald Test

A complete guide to the Wald Test for testing a single parameter (or a set of parameters) in a maximum likelihood model-formula, hypotheses, assumptions, hand-worked numerical examples, the relationship to the t-test and z-test, and a Python (statsmodels) walkthrough for regression coefficient testing.

Diagram of a residuals-versus-fitted-values scatterplot showing a curved, non-linear spread of points, illustrating the broader class of heteroskedasticity patterns that White's Test for Heteroskedasticity is designed to detect.
Article · July 2026

White's Test for Heteroskedasticity

A complete guide to White's Test for Heteroskedasticity-formula, hypotheses, assumptions, hand-worked numerical examples, and a statsmodels.stats.diagnostic.het_white Python walkthrough for detecting heteroskedasticity in regression residuals without assuming a linear variance pattern.

Diagram showing paired before-and-after measurements ranked by absolute difference and split by sign, illustrating how the Wilcoxon Signed-Rank Test summarizes within-subject change without assuming normality.
Article · July 2026

Wilcoxon Signed-Rank Test

A complete guide to the Wilcoxon Signed-Rank Test-formula, hypotheses, assumptions, hand-worked numerical examples, effect size, and a scipy.stats.wilcoxon Python walkthrough.

Diagram showing two machine learning models evaluated across several datasets, with each dataset's performance difference ranked by absolute size and split by sign, illustrating how the Wilcoxon Test for Model Comparison summarizes which model tends to win without assuming normally distributed differences.
Article · July 2026

Wilcoxon Test for Model Comparison

A complete guide to using the Wilcoxon Signed-Rank Test to compare two machine learning models-formula, hypotheses, assumptions, hand-worked numerical examples across multiple datasets, effect size, and a scipy.stats.wilcoxon Python walkthrough for statistically comparing model performance.