Lecture 15

Lecture 15 - carry a credit card balance from month to...

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Population Proportions Population Parameter: p - population proportion Sample Statistic: p ˆ = X where X is a binomial n random variable Sampling Distribution of p ˆ Mean µ p ˆ = p Standard Deviation σ p ˆ = q p ˆ ˆ / n where q ˆ = 1 – p ˆ The distribution of p ˆ will be approximately normal when n is large. This means we can convert to standard normal (or z) and use standard normal table for probabilities.

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Population Proportions Hypothesis Testing Test Statistic z = sample statistic – population parameter standard error z* = p ˆ - p 0 p 0 q 0 n
Example 1 In a 1998 article, the credit card industry asserted that at most 50% of college students

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Unformatted text preview: carry a credit card balance from month to month. In a random sample of 310 college students, 217 carried a balance each month. Is this sufficient evidence to refute the industry’s claim? α = .01 Hypotheses: H : p = .5 ( p ≤ .5) vs. H A : p > .5 Test Statistic: Example 2 46% of Americans said they do not trust the media when it comes to “reporting the news fully”. In a poll of 1,000 Americans, 491 said they did not trust the media. At the α = 0.05 level is there evidence to indicate that the percentage has increased?...
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This note was uploaded on 02/15/2009 for the course STAT 2004 taught by Professor Melutz during the Fall '07 term at Virginia Tech.

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Lecture 15 - carry a credit card balance from month to...

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