Math 151 , Fall 2007 Friday Day 21, Oct. 12 Hit reload....belated after class, sorry!.

HW:  (Re) read pp. 133-136.  Skip Chapter 6. Read p. 186.  Read Chapter 8.  Read p. 200 (Other designs) last (optional).  Check p. 206, 8.17-22, 26 at first., then 8.23-25 with Table B.  Next, Chapter 9.
Hand in
p. 199 8.9 Apartment living, SRS. Use Table B.
p. 209, 8.36 Area code sample, SRS  Use Table B.
p. 211, 8.45 random digit dialing
p. 210, 8.41 random digit characteristics p.209-10, 8.38 b only Traffic lights
p. 208, 8.30 movie viewing
+ + + + Rest should have been posponed!+ + + +
p. 205, 8.16, Ask more people
p. 212, 8.50, Polling Hispanics		 Read, to discuss 

p. 211, 8.47 guns

p. 204, 8.14, 8.15 biases.
p. 208, 8.31 world affairs
p. 211, 8.46 wording survey questions

p. 212, 8.49 Canada healthcare

Optional 


p. 209, 8.35 Use table B (more practice)

p. 209, 8.34 seat belt use

Exams returned today.  Problem 0: 5 points for showing up.

problem # total
    0   1    2
    3    4    5  6      7
     
10|0
possible 100  5 12 13 26 10 9 3 22
  9|11334688
max 100 5 12 13 26 10 9 3 22
  8|3467
Q3 85 5 12
 13 26 10 9 3 19
  7|1369
Med 75 5 12 13 24 9 9 3 13
  6|39
Q1 63 5 9 12 20 7 8 1 7
  5|14
min 41 5 3 8 10 1 4 0 1
  4|1

Solutions
Many people still having major difficulties with Normal distribution, especially tables.
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
Sign-in sheet: If you did p.199, 8.10, write your # of managers with Asian names next to your initials.
Homework questions?  Day 20

Ch. 8&9:  Producing Data:  Aim:  create data sets that will allow us to make inferences to a larger world than just the data we have.

 Recall:  Details See Day 20
Observational Study: vs.   Experiment: ; Confounding: 

Ch. 8 p. 192ff.  Sampling 
Population /Sample:   Hope:  Sample will be representative of the population.
>> Sampling design:  Describes exactly how sample is to be chosen from population.

(SAMPLING) BIAS:  The design of a study is biased if it systematically favors certain outcomes.
Checked our "sample" of digits:  People systematically favor 7's, 3's?  Stay away from 1, 9, middle.

Non-probability samples (sampling badly):  Voluntary response sample, Convenience sample

Simple Random Sample (SRS) of size n:  n individuals chosen in such a way that every possible set of n individuals has an equal chance of being chosen.   A probability sample (p.200).
HOW?  A chance mechanism: cards, Applet (simulated Lotto balls) or
NEW today:
Table of random digits  See Day 20 for notes. (Table B, p.686)
 
Some more sources of bias, even in probability samples (p. 201-3):  Day 20
**Undercoverage:    (Sometimes Sampling frame:)
** "Nonresponse".
**Response bias
**Wording of questions
+ + + + + +got to here Friday + +
Use the sample to make an inference about the population: Larger (RANDOM) samples give more accurate results than smaller random samples.  (Size of sample, not proportion of population, matters.)
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