## What are the 4 non-parametric tests?

The main nonparametric tests are:

- 1-sample sign test.
- 1-sample Wilcoxon signed rank test.
- Friedman test.
- Goodman Kruska’s Gamma: a test of association for ranked variables.
- Kruskal-Wallis test.
- The Mann-Kendall Trend Test looks for trends in time-series data.
- Mann-Whitney test.
- Mood’s Median test.

## What is NPAR1WAY SAS?

The NPAR1WAY procedure performs nonparametric tests for location and scale differences across a one-way classification. PROC NPAR1WAY also provides a standard analysis of variance on the raw data and tests based on the empirical distribution function.

**What is the Kruskal-Wallis test based upon?**

The Kruskal-Wallis H test (sometimes also called the “one-way ANOVA on ranks”) is a rank-based nonparametric test that can be used to determine if there are statistically significant differences between two or more groups of an independent variable on a continuous or ordinal dependent variable.

### Is normality an assumption of parametric test?

Assumption 1: Normality Parametric tests assume that each group is roughly normally distributed. If the sample sizes of each group are small (n < 30), then we can use a Shapiro-Wilk test to determine if each sample size is normally distributed.

### Why is normality important in parametric tests?

For the continuous data, test of the normality is an important step for deciding the measures of central tendency and statistical methods for data analysis. When our data follow normal distribution, parametric tests otherwise nonparametric methods are used to compare the groups.

**What is the difference between Mann Whitney and Kruskal Wallis?**

The major difference between the Mann-Whitney U and the Kruskal-Wallis H is simply that the latter can accommodate more than two groups. Both tests require independent (between-subjects) designs and use summed rank scores to determine the results.

## What is Proc Ttest in SAS?

The SAS PROC TTEST procedure is used to test for the equality of means for a two-sample (independent group) t-test.

## What is n In Proc means?

Var q1 – q5 ; Run; N refers to number of non-missing values and NMISS implies number of missing values. PROC MEANS – Missing.