Page 20 - Intermediate Statistics for Dummies

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Table of Contents
Part V: Rebels without a Distribution..........................259
Chapter 16: Going Nonparametric . . . . . . . . . . . . . . . . . . . . . . . . . . . . .261
Arguing for Nonparametric Statistics........................................................261
No need to fret if conditions aren’t met ..........................................262
The median’s in the spotlight for a change.....................................263
So, what’s the catch?..........................................................................265
Getting the Basics of Nonparametric Statistics .......................................265
Sign.......................................................................................................266
Rank......................................................................................................267
Signed rank..........................................................................................268
Rank sum .............................................................................................270
Chapter 17: The Sign Test and Signed Rank Test . . . . . . . . . . . . . . . . .271
Reading the Signs: The Sign Test ...............................................................271
Testing the median.............................................................................273
Estimating the median.......................................................................275 xvii
Testing matched pairs .......................................................................278
Going a Step Further with the Signed Rank Test......................................279
A limitation of the sign test...............................................................280
Stepping through the signed rank test ............................................280
Losing weight with signed ranks ......................................................282
Chapter 18: Pulling Rank with the Rank Sum Test . . . . . . . . . . . . . . .285
Conducting the Rank Sum Test ..................................................................286
Checking the conditions....................................................................286
Stepping through the test..................................................................287
Stepping up the sample size .............................................................288
Performing a Rank Sum Test: Which Real Estate Agent Sells
Homes Faster?...........................................................................................289
Checking the conditions for this test...............................................290
Testing the hypotheses .....................................................................291
Chapter 19: Do the Kruskal-Wallis and Rank the Sums
with Wilcox . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .295
Doing the Kruskal-Wallis Test to Compare More than Two
Populations ...............................................................................................295
Checking the conditions....................................................................297
Setting up the test ..............................................................................299
Conducting the test step by step .....................................................299
Pinpointing the Differences: The Wilcoxon Rank Sum Test....................302
Pairing off with pairwise comparisons............................................303
Carrying out comparison tests to see who’s different ..................303
Examining the medians to see how they’re different ....................304