# Permutation Tests

• Oct 3rd 2012, 02:14 PM
renolovexoxo
Permutation Tests
The sorted values in the randomization distribution are:
-0.95 -0.95 -0.94 -0.87 -0.86 -0.86 -0.83 -0.81 -0.81 -0.80
-0.79 -0.77 -0.77 -0.76 -0.76 -0.74 -0.74 -0.74 -0.74 -0.74
   960 more values   
0.74 0.75 0.76 0.76 0.76 0.78 0.80 0.81 0.81 0.82
0.82 0.82 0.84 0.90 0.90 0.90 0.94 1.01 1.02 1.10
(a) 2 pts. What is the observed value of the test statistic used in the randomization test?
(b) 5 pts. Compute the randomization-based two-sided p-value for testing the null hypothesis
of no e ffect of washing. If you have insufficient information, indicate what addition information you need.

I'm not sure how to calculated a randomization test without the actual data. Could anyone explain the process to me?
• Oct 3rd 2012, 10:42 PM
chiro
Re: Permutation Tests
Hey renolovexoxo.

Can you be more specific about the kind of test you are referring to? Randomization suggests you are using a simulation method based on some sample data, but there are many different kinds of simulation methods that you can use.

A permutation test is where you calculate all possible sample combinations under a combinatorial constraint and then use this to get a distribution of test-statistics which you apply a rejection region to to either reject or fail to reject a particular hypotheses.

What kind of technique are you looking at?
• Oct 5th 2012, 07:08 AM
renolovexoxo
Re: Permutation Tests
This was about all the problem said, I am assuming that it is a permutation test, since that is all we learned about in class. That's how I had hoped to proceed, but I don't know how.
• Oct 5th 2012, 08:13 PM
chiro
Re: Permutation Tests
You usually don't use permutation tests when you have a huge sample size: there's no real point for this.

You need to give more context for the question: what does this distribution of numbers represent? What are the null and alternative hypotheses in relation to the data and what the data represents?
• Oct 7th 2012, 07:55 AM
renolovexoxo
Re: Permutation Tests
I wouldn't if I had a choice, this is my question that I have to answer.