<unk>  are<unk>  where it is not assumed that the population fits any<unk> ed distributions.<unk>  are typically applied to populations that take on a ranked order (such as movie reviews receiving one to four stars).
The branch of<unk>  known as<unk>  is concerned with<unk> l models and<unk> l tests.<unk><unk>  models differ from<unk>  models in that the model structure is not specified a priori but is instead determined from data. The term<unk><unk>  is not meant to imply that such models completely lack parameters but that the number and nature of the parameters are flexible and not fixed in advance.<unk><unk>  models are therefore also called distribution free or parameter-free.
A histogram is a simple<unk><unk>  estimate of a probability distribution
Kernel density estimation provides better estimates of the density than histograms.<unk><unk>  regression and semiparametric regression methods have been developed based on kernels, splines, and wavelets.<unk><unk>  (or distribution-free) inferential<unk> l methods are mathematical procedures for<unk> l hypothesis testing which, unlike<unk><unk> , make no assumptions about the frequency distributions of the variables being assessed. The most frequently used tests include
binomial test
Anderson-Darling test
chi-square test
Cochran's Q
Cohen's kappa
Efron-Petrosian Test
Fisher's exact test
Friedman two-way analysis of variance by ranks
Kendall's tau
Kendall's W
Kolmogorov-Smirnov test
Kruskal-Wallis one-way analysis of variance by ranks
Kuiper's test
Mann-Whitney U or Wilcoxon rank sum test
McNemar's test (a special case of the chi-squared test)
median test
Pitman's permutation test
Siegel-Tukey test
Spearman's rank correlation coefficient
Student-Newman-Keuls (SNK) test
Wald-Wolfowitz runs test
Wilcoxon signed-rank test.<unk><unk>  tests have less power than the appropriate<unk>  tests, but are more robust when the assumptions underlying the<unk>  test are not satisfied.
Non-parametric statistics
Ancillary statistic
Shapiro-Wilk test
Kendall tau rank correlation coefficient
Likelihood-ratio test
Linear regression
Analysis of covariance
Analysis of variance