Under what conditions is nonparametric test suggested?

Under what conditions is nonparametric test suggested?

When the sample size is small and the distribution of the outcome is not known and cannot be assumed to be approximately normally distributed, then alternative tests called nonparametric tests are appropriate.

Why do we use nonparametric test explain with examples?

Non parametric tests are used when your data isn’t normal. Therefore the key is to figure out if you have normally distributed data. For example, you could look at the distribution of your data. If your data is approximately normal, then you can use parametric statistical tests.

Can a non-inferiority trial show superiority?

In a non-inferiority trial, the focus is on the lower bound margin, what happens at the upper end is not of primary concern in this type of trial design. One can also declare superiority in a non-inferiority trial if the lower limit of CI of the new treatment is above the non-inferiority margin and above zero.

What is a good non-inferiority margin?

In order to demonstrate non-inferiority, the recommended approach is to pre-specify a margin of non- inferiority in the protocol. After study completion, a two-sided 95% confidence interval (or one-sided 97.5% interval) for the true difference between the two agents will be constructed.

What is the null hypothesis in non-inferiority trial?

The null hypothesis in non-inferiority trials is that new treatment is inferior to standard treatment. The alternative hypothesis is the new treatment is non-inferior to standard treatment.

How many groups can a non parametric test show?

Here’s the specific question and my quick answer: My colleague is applying non parametric (Kruskal-Wallis) to check for differences between groups. There are 12 groups and test showed that there is significant difference in the groups.

How to do multiple comparisons in nonparametric tests?

A simple approach could be: If you want to know differences between pairs, you could do Mann-Whitney U tests for each pair or test for correlations using a spearman rho for instance. The correction for multiple comparisons should be applied on results for those tests especially if you haven’t predefined hypotheses.

Are there any comparable post-hoc tests in nonparametric approach?

There are 12 groups and test showed that there is significant difference in the groups. However, to check which pair is significant is tedious and I’m not sure if there is comparable post-hoc test in non-parametric approach. Any resources available in hands?

How is a Bonferroni correction used in a non parametric test?

Bonferroni correction is your only option when applying non-parametric statistics (that I’m aware of). Or, actually, any test other than ANOVA. A Bonferroni correction is actually very simple. Just take the number of comparisons you want to make, then multiply each p-value by that number.