Nonparametric tests

Sign test

Wilcoxon signed-rank test


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Wilcoxon rank-sum (Mann–Whitney) test

Equality of medians

Kruskal–Wallis test

Kolmogorov–Smirnov test

Binomial probability test

Chi-squared tests for association

Tests for trend

One- and two-sample tests of proportions

Test for random order

Equality of survivor functions

Equality of ROC areas

Equality of ROC area against a standard ROC curve


Interrater agreement


Quantile regression

Median regression

Least absolute deviations regression

User-specified quantiles

Koenker and Bassett and Huber sandwich standard errors with many choices of bandwidth methods and kernels

Simultaneous quantile regression

Interquartile range regression


Nonparametric correlation coefficients

Spearman’s rank order

Kendall’s rank order



Nonparametric regression 

Multiple covariates supported

Continuous covariates (8 kernels available)

Discrete covariates (2 kernels available)


local constant regression

local linear regression

Point estimates with SEs and CIs

Derivative estimates with SEs and CIs

Automatic optimal bandwidth selection

Interface to margins for advanced inference

Estimates of population-averaged and subpopulation-averaged means and effects

Fully conditional means and effects at any specified values of the covariates

Confidence intervals


Graphs via marginsplot

Watch Nonparametric regression.


Survival analysis

Kaplan–Meier curves

Nelson–Aalen curves

Logrank and other tests of equality


Treatment effects

Nearest-neighbor matching

Propensity-score matching


Resampling and simulations

Bootstrap sampling and estimation

Sampling with replacement

Monte Carlo simulations



Univariate kernel density estimation

Lowess smoothing

Kernel-weighted local polynomial smoothing

Robust nonlinear smoother


ROC analysis

Adjust for covariates

Plot ROC curves


Centiles and confidence intervals

Estimate percentiles

Exact confidence intervals

Optionally assume normality