1. Lecture 4 Section 1.4.3 Wed, Sep 1, 2004
What’s in the Bag?
Lecture 4
Section 1.4.3
Wed, Sep 1, 2004

2. How Strong is the Evidence?
Rather than give an accept/reject answer, we may ask a different question:
How strong is the evidence against H0?

3. The p-value
p-value – The likelihood of getting by chance, if H0 is true, a value at least as extreme as the one observed.

4. Two Bags
Bag A
-1000 10 20 30 40 50 60
1000
Bag B
-1000 10 20 30 40 50 60
1000

5. Interpretation of the p-value
Smaller p-values
Larger p-values 1
p-values

6. Interpretation of the p-value
Larger discrepancy
Smaller discrepancy 1
p-values

7. Interpretation of the p-value
Stronger evidence
against H0
Weaker evidence
against H0 1
p-values

8. Interpretation of the p-value
Statistically significant
Statistically insignificant 1
p-values

9. Let’s Do It! Let’s do it! 1.7, p. 26 – Chromium Supplements.
Let’s do it! 1.8, p. 27 – Three Studies.

10. Let’s Do It!
Let’s do it! 1.9, p. 32 – p-value for a One-Sided Rejection Region to the Left.
Example 1.8, p. 33 – p-value for a Two-Sided Rejection Region.
Let’s do it! 1.10, p. 34 – p-value for a Two-Sided Rejection Region.
Example 1.9, p. 36 – Can You Picture the p-value?

11. Let’s Do It!
Let’s do it! 1.11, p. 39 – Machine A or Machine B?