Unit 7 Sampling Distributions 7.2 The Sampling Distribution of the Sample Proportion.

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Presentation transcript:

Unit 7 Sampling Distributions 7.2 The Sampling Distribution of the Sample Proportion

p = 0.10 n = samples Not roughly symmetric!

p = 0.10 n = samples Still not symmetric.

p = 0.10 n = samples Approaching symmetric.

p = 0.10 n = samples Pretty symmetric

p = 0.22 n = samples Pretty symmetric. But n =30? No, the number of samples is not relevant!

p = 0.22 n = samples Pretty symmetric. And maybe something more!

p = 0.22 n = samples Pretty symmetric. And maybe something more!

How do we get the shape of the sampling distribution to resemble a Normal distribution?

It depends on BOTH the value of p and the size of the sample n.

Unit 7 Sampling Distributions 7.2B The Sampling Distribution of the Sample Proportion

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Example 1: Hepatitis occurs in 7% of all patients who receive blood transfusions during heart surgery (as of 2003). Suppose that only 6 of 200 random patients contract hepatitis after such surgery. How unusual is this?

Example 2: Suppose 20% of the subscribers of a cable company watch a certain shopping channel. A survey of 125 subscribers will be taken. If greater than 25% of the sample indicates that they watch this channel then the cable company will keep it. What is the approx probability that the cable company will keep the channel?

Example 3: Suppose that a particular candidate for public office is in fact favored by 52% of all registered voters in the district. What is the probability that a SRS of size 400 will produce a result within 3 percentage points of the true value of support for this candidate?

Example 4: Do you have ESP?

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