Math 151 , Spring 2005, Day 33 Friday, Nov. 11 Hit reloadAfter class

Exam 3, Friday Nov. 18  (Day 36)  Covers Part IV (what we did), and V thru Monday Day 34Handout: Sample problems.
Day 33: Reading:  Chapter 20+21 thru p. 392 (Activstats is good here too.)  Then continue (Alpha levels) through p.397.  Lightly through Power . Read What can go wrong p. 401 and the rest. (SPSS won't do proportion computations, but some other programs do; it's good to have an idea what you might see, p. 402.)
Please respond to my email about the textbook choice!
Hand in (All D&V)

Chapter 20, p. 386: 
1, 2 (change c to "...sure that more than 60% of the people like...",) Hypotheses
3  Negatives (meaning of P)  d is gibberish, tho the back of the book says it's correct! 
4  Dice (Meaning of P) I think the problem is badly presented!  The null hypothesis they are using is that the die is fair; we want to collect evidence to assess the strength of the seller's claim that it is loaded.  (Saying "we don't believe" his claim could make it look like his claim that it's loaded should be the null.  But actually, we are  skeptics who demand evidence against the fair-die null hypothesis before we buy; we also do the test.) 
5, 6 Relief, Cars (Conclusions from P), 
9 Dowsing (doing a test)
13 Pollution (doing it)
19 Women executives
22 Acid rain (inc. CI)
A. a) Use your greeen shoebox result to do a One-sided test against the null hypothesis p = .5, with alternative HA: p < .5.
+ + + + + + + + + + Postpone the rest (two sided)
    b) Use your greeen shoebox result to do a Two sided test against the null hypothesis p = .5.
7, 8 Find the mistakes
From ActivStats, copied here:
 MRA-304-2:  Kerrich Coin Toss  While he was a prisoner of the Germans during World War II, the British statistician John Kerrich tossed a coin 10,000 times.  He got 5067 heads.  Take Kerrich's tosses to be an SRS from the population of all possible tosses of his coin.  If the coin is perfectly balanced, p = 0.5.  Is there reason to think that Kerrich's coin was not balanced?

 Read,
  to 
discuss 		 Op
tion
 al 
Please respond to my email about the textbook choice!  I have (a little) under 50% response---
Exam 3 a week from today.Handout: Sample problems.

Homework questions? Day 32
Tests: notes Day 32   Brief summary...
(NULL Hypothesis Ho : (Straw man we collect evidence against. Status quo.)
  Assume Ho is true.  Look at evidence (data).  Is it inconsistent with Ho ? Then Reject Ho .  <>
  Ho : a specific model for the population, with a specific parameter value.  =
HA :  (alternative hypothesis:  What you hope /fear /would like to prove)   <, >, NOT =
IF Ho  is true: how far out (weird) is your p-hat?
P-value:  The probability, assuming Ho  is true, of observing the result we have (or one more extreme)--if we could do the experiment again...  Strength of evidence against Ho(thus for HA) <>
    For One-sided alternatives, P-value is the single "tail" beyond our observed statistic,  in the direction of the alternative hypothesis.
Start here Monday:
For a Two-sided alternative, P-value is (usually) "double the tail" beyond our observed statistic, because we could be "as or more extreme" in either direction!   (Measuring how weird our observation is, if  Ho is the case.)
A test doesn't tell how much the data is different from the null hypothesis.  Use a CI for that!
<>

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