33k views

### What is the difference between a parametric test and non-parametric tests? [duplicate]

Please explain the difference between a parametric and a non-parametric test. Do all data mining techniques come under the non-parametric category?
72 views

### Interpretation of the Mann-Whiteny U test [duplicate]

The straightforward null hypothesis for the Mann-Whitney U test is that the two distributions are identical. However, many documents (including Wikipedia) also indicate that it is equivalent for ...
167k views

### How to understand degrees of freedom?

From Wikipedia, there are three interpretations of the degrees of freedom of a statistic: In statistics, the number of degrees of freedom is the number of values in the final calculation of a ...
138k views

### How would you explain covariance to someone who understands only the mean?

...assuming that I'm able to augment their knowledge about variance in an intuitive fashion ( Understanding "variance" intuitively ) or by saying: It's the average distance of the data ...
48k views

### Difference Between ANOVA and Kruskal-Wallis test

I am learning R and have been experimenting with analysis of variance. I have been running both kruskal.test(depVar ~ indepVar, data=df) and ...
19k views

### Why is Pearson parametric and Spearman non-parametric

Apparently Pearson's correlation coefficient is parametric and Spearman's rho is non-parametric. I'm having trouble understanding this. As I understand it Pearson is computed as  r_{xy} = \frac{...
8k views

### Is there any statistical test that is parametric and non-parametric?

Is there any statistical test that is parametric and non-parametric? This question was asked by an interview panel. Is it valid question?
13k views

### Unequal variances t-test or U Mann-Whitney test?

I have two independent samples and I need to compare their values, to say if values in the first group are higher than values in the second group. I performed the Levene's test and the variances are ...
8k views

### How many « degrees of freedom » should a Wilcoxon rank-sum test have?

I would like to perform a Mann-Whitney U Test (also called Wilcoxon rank-sum test) on a weighted sample in R. Such a non-parametric test is required, as neither of the two variables used follow normal ...
2k views

### Effect size for Wilcoxon signed rank test that incorporates the possible range of the attribute

I'm currently working on my master thesis and I'm analysing attributes obtained from digital elevation models (DEMs). I try to compare two point sets for which I extracted altitude values from two DEM ...
5k views

### Wilcoxon Rank Sum (Mann Whitney) test-SAS Results Interpretation

I need a clarification on interpreting Wilcoxon Rank Sum (Mann Whitney) test results using SAS. Here is a sample results look like. I am trying to form a hypothesis and interpret the results. In this ...
1k views

### Wilcoxon rank sum test methodology

I'm comparing the performance of two algorihtms $A$ and $B$ based on a metric. For each algorithm, I have $31$ independent samples that represent its performance. This samples are grouped in two ...
601 views

### what is the meaning of 'normality' as a difference between parametric and nonparametric method? [duplicate]

I'm so confused of the definition of the terminology, "normality". I mean, normality of what? According to central limit theorem, regardless of the distribution of population,the computed values of ...