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StatsHWNY

# StatsHWNY - Show me your work(4pts a M = 14.22 S =.93 S x...

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Nick Yidiaris 10/28/09 HW #6 1. When would the mean grade in a class on a final exam be considered a statistic? When  would it be considered a parameter? Be specific. (2pts) 2. Why is a 99% confidence interval wider than a 95% confidence interval? (1pt)       3. How does the t distribution compare with the normal distribution? How does this difference  affect the size of confidence intervals constructed using z relative to those constructed using  t? Does sample size make a difference? How? (3pts)       4. A population is known to be normally distributed with a standard deviation of 2.8. a) Compute the 95% confidence interval on the mean based on the following sample of nine:  8, 9, 10, 13, 14, 16, 17, 20, 21. b) Now compute the 99% confidence interval using the same data.

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Unformatted text preview: Show me your work. (4pts) a. M = 14.22 S = .93 S x 1.96 = 1.82 Interval is 12.4 – 16.04 5. State the null hypothesis for (4pts): a) An experiment testing whether echinacea decreases the length of colds. b) A correlational study on the relationship between brain size and intelligence. c) An investigation of whether a self-proclaimed psychic can predict the outcome of a coin flip. d) A study comparing a drug with a placebo on the amount of pain relief. (A one-tailed test was used.) 6. Is it more conservative to use an alpha level of .01 or an alpha level of .05? Explain. (1pt) It is more conservative to use an alpha level of .01 because you are taking a more strict stance on what data is considered to be significant....
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