Other's OnLine Resources (Chapter 18)
Wilcoxon's
MatchedPairs SignedRanks Test 
 Description:
In using this interactive online resource, you'll be able to
enter hypothetical sets of matched data and then see the plevel
that's computed for your data. By varying the nature of
your data sets, you'll come to understand why the Wilcoxon test
sometimes leads to a statistically significant result.
 What to Do:
 Click on the colored title of this online resource: "Wilcoxon's
MatchedPairs SignedRanks Test."
 On the screen that pops up, Not that there's a white box
with two columns of scores.
 In the white box, imagine that each row of scores corresponds
to a different high school students who wants to go to college.
Further imagine that the specific numbers are SAT scores and
that 2 numbers appear on each row because each of our 9 hypothetical
students took the SAT twice.
 Change the last student's second score from 582 to 537.
 Click on the "Submit" button, and then examine the plevel
that's presented above the box containing the paired data.
Originally the plevel was 0.0396
 Originally the plevel was 0.03906; now, it's equal to .09766.
Think about the one change in the data you made, consider
all 9 pairs of scores, and ask yourself whether it makes sense
that the plevel got larger because of the change you made.
 Make other changes in the data, each time checking to see
what happens to the resulting plevel. (To make the original
9 pairs of scores to appear in the white data box, click on
"Return to Statistics" in the upper lefthand corner of the
screen, and thenon the new screen that pops upclick on
"Wilcoxon MatchedPairs SignedRanks Test" under the heading
"OneSample and MatchedPairs Tests.")
 Sky Huck's Puzzle Question:
If you start with the original 9 pairs of scores (by clicking
on the "Reset" button, you'll note that you can increase the first
student's 2nd score (of 594) by 1 point, by 10 points, or by 100
points, and yet these changes do not alter the plevel. Why does
the plevel remain constant even though this score is changed?
(If you answer this question correctly, you'll probably be able
to sense how extensively you could LOWER 594 without affecting
the plevel.)

