Download presentation

Presentation is loading. Please wait.

Published byJohn Mealing Modified over 2 years ago

1
Non-parametric test Introduction, Wilcoxon rank sum test and Man-Whitney U test Reporter: Shao-Li Han

2
Non-Parametric Test Parametric tests: certain assumptions Non-parametric tests: fewer assumptions need

3
Advantage Few or no assumption Reduce the effect of the outlies Even for ordinal and sometimes even nominal data Nominal data: Ex. Marriage status: single, marriage, devoiced, widow… Ordinal data: Ex. The academic performance: A, B, C, D and E

4
Statistic Character No estimate of variance No confidence interval Fewer measures of effect size Chi-Square test of independence is one of non-parametric statitics Median, instead of the mean Not as powerful as parametric alternatives!!

5
Sign Test When to apply: conditions that single sample t-test are not met. Binomial test Example 1

6
Observation Use less number One tail or 2 tails =>excel function, =binomdist provided one tail probablity Not for ranked-signs, for example 1, there should be different influence in “50” and “25” on the result, although the signs of the two value are all “1”. Wilcoxon’s ranked-sign test!

7
Wilcoxon Rank Sum Test for Independent Samples 2 independent samples are drawn from populations with an ordinal distribution. H0: the observations come from the same population. The probability when x 0 > y 0 and x 0

8
Different sample size A bit more care is required W represents the left tail static; W’ for right tail statictic Using reverse ranking Example

9
If 2 samples are sufficiently large Sample size > 10 or greater than 20 Wilcoxon table W statistic is approximately normal N(μ,σ) Example 3

10
Effect Size Given by the correlation coefficient (M1-M2)/Standard deviation

11
Mann-Whitney U Test Alternative form of Wilcoxon rank-Sum test No matter which sample is bigger!! Mann-Whitney TablesTables Observed value of U Reject the hypothesis Mathematic processing …ex. U1+U2=n1*n2… Examples…

12
Example ADHD vs non-ADHD children Academic performance, A, B, C among students from a given grade 1 elementary school. By using Wilcoxon rank sum test or Mann-Whitney U test Sample size > 20 (in excel file)

Similar presentations

OK

Lesson 15 - R Chapter 15 Review. Objectives Summarize the chapter Define the vocabulary used Complete all objectives Successfully answer any of the review.

Lesson 15 - R Chapter 15 Review. Objectives Summarize the chapter Define the vocabulary used Complete all objectives Successfully answer any of the review.

© 2017 SlidePlayer.com Inc.

All rights reserved.

Ads by Google

Ppt on office management system Ppt on school management system software Ppt on cloud gaming Ppt on cement industry analysis Ppt on networking related topics on meteorology How to view ppt online Download ppt on recession in india Ppt on civil engineering structures Water level indicator using seven segment display ppt online Ppt on bluetooth and wifi