students would be required to ensure that a 95% confidence interval estimate for the mean caffeine intake (measured in mg) is within 15 units of the true mean? Assume that the standard deviation in caffeine intake is 68 mg. 3. Consider the study proposed in problem #2. How many students would be required to estimate the proportion of students who consume coffee? Suppose we want the estimate to be within 5% of the true proportion with 95% confidence. 9.3 Practice Problems # Hours # AVG
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The Role Of Research and Statistics In Psychology Statistical Reasoning in Psychology Research and Statistics in Psychology Research and Statistics play an important role in psychology. Researchers in the field of psychology study what people will do or how they will react in any situation. Since not everyone reacts the same to a certain situation, statistics is used to see if a certain action happens often enough to come to an idea about cause and effect. It used to be believed
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employees willing to participate. As well knowing what sampling method and frame are needed to determine the sampling size. To determine the sampling there are two key items needed are confidence interval and confidence level. The confidence level simply is how accurate can the information be. The confidence interval, margin of error, is finding the amount of maximum amount of error within the sampling group. For this sampling group has been found the size will be determined by the employees which
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Suppose a 95% confidence interval for μ turns out to be (1,000, 2,100). Give a definition of what it means to be "95% confident" in an inference. A) In repeated sampling, the population parameter would fall in the given interval 95% of the time. B) In repeated sampling, 95% of the intervals constructed would contain the population mean. C) 95% of the observations in the entire population fall in the given interval. D) 95% of the observations in the sample fall in the given interval. 3
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variance, and standard deviation for a discrete random variable. Ch-8: ( Learning Objectives: Only Section 2) 1. Know how to construct and interpret an interval estimate of a population mean and / or a population proportion. 2. Understand and be able to compute the margin of error. 3. Learn about the t distribution and its use in constructing an interval estimate whenis unknown for a 4. Be able to determine the size of a simple random sample necessary to estimate a population mean and/or a population
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Business 206 August 16, 2011 Statistics project ABC Commercial lengths vs MTV The goal of this study was to test the hypothesis; MTV commercials are longer than ABC commercials. To do this the study was designed to be Quantitative: consist of numeric measurements and counts. Our study is measured in seconds so it was Quantitative. The level of measurement used Ratio; because in this study a zero entry is an inherent zero and not just a place on a scale. You cannot for example have -5 seconds
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TICKET PRICES UEFA League final tickets are the most prestige tickets in the world. After doing a sample of 240 punters who have premier seats for the UEFA League Final match, it was determine that many people are paying more than the face value of $1,100, but they are not paying more than $1,500. UEFA League officials sell out tickets each year for the UEFA League Final match within a month of releasing tickets. However, most tickets are resold to third and possibly fourth parties.
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techniques to analyze sample information from a certain population to improve our knowledge about the population. Measures of central tendancy and variability fall under descriptive statistics. Inferential statistics is divided into two i.e confidence interval which give a range of values for unknown parameters of a population by measuring a statistical sample and the test of significance also called hypothesis testing whereby a claim about a population is tested by analyzing a statistical sample
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to 2 decimal places) Confidence level the interval is 68.26% 3. Let X be the value of the population. a) b) c) d) x ± Z 0.2 σ x x ± Z 0.1 σ x x ± Z 0.05 σ x x ± Z 0.02 σ x = = = = x ± 0.84σ x x ± 1.28σ x x ± 1.64σ x x ± 2.05σ x 4. Let X be the waiting time of the customer. a) b) c) σ = 5/2 = 2.5, x = 25 x ± Z0.025 σ = 25 ± 1.96 (2.5) = (20.10, 29.90) minutes σ = 5/3 = 1.6667, x = 15 x ± Z0.025 σ = 15 ± 1.96 (1.6667) = (11.73, 18.27) minutes Confidence interval is used to estimate a
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1. (20 pt) Go to http://www.stat.tamu.edu/~west/ph/sampledist.html. Use a skewed distribution. Take 1000 samples of sizes 2, 10 and 100. Construct a mean for each sample and look at the distribution of the sample means (third row). Record the mean and SD in the population for the original random variable. Make a table and record the mean of the means, and the standard deviation of the mean for each sample size (2, 10 and 100). For a bell-shaped distribution we showed that the mean of the sample
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