Understanding Statistics					 J.R. Rasmussen

					Class 10 Outline

I) Today's Class:  Extended assignment 4 will be due on Wednesday 11/04/09

	A) Putting it all together
		1) sampling distributions
		2) The normal probability distribution
		3) The central limit theorem

	B) Application: Our New York times poll

	C) Today we will be right in the middle of the swamp


II) Recap of last class: Putting it all together

	A) General picture: real world vs random variable world

	B) Sampling Distributions
		1) random variable X
		2) random sample from X of size n
		3) We look at the mean of the sample: a new random variable
		4) Rule 1 and 2 for the mean and standard deviation of 				the new variable which is the mean of the sample


III) Putting it all together (continued)

	C) The normal distribution
		1) Rule 3
		2) Rule 4  (very, very important)

	D) combining rule 1,2, and 4 into the central limit theorem


	E) Application: statistical inference, New York Times poll 	revisited
		1) How we view poll results as a binomial distribution
			a) Pr(success)= “pi”, n=the size of our poll
				i) calculate mean and standard deviation of X
				ii) what the sample mean distribution is
				iii)use rules 1 and 2
			b) the proportion of people who favor a candidate
			How to view
			c) apply to our poll with n=100 and “pi” =.4


		2) New York times had a sample 979 people
		
			a) We were left with two questions
				i) where did the .03 come from
				ii) where did the 19 out of 20 come from
			b)Rule 4 and the 19/20 probability
				i) calculate how many standard deviations .03 is
				ii) calculate the z value and the probability

		3) Recall the histogram from our data to justify central limit theorem

		4)Relate our example to the general picture of real world vs random variable world


IV) BREAK


V) Group exercise

	A) problem 8.10 b, pages  357-358

	B) problem 8.16, page 358

	C) problem 8.23 a,e,  page 364

	D) problem 8.27 a,b,  page 365


	E) find how large a sample size we would need to have a 90% 	probability of being ±.02


VI) Remember assignment 4 extended due Wednesday 11/04/09