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Unformatted text preview: ECO 220Y Lecture19 Sampling Distribution – Part 3 Sample Proportion Migiwa Tanaka Reading: 9.2 1 Outline efinition: Sample Proportion Definition: Sample Proportion Normal Approximation of Binomial Distribution Sampling Distribution of a Proportion Normal Approximation of Sampling Distribution of a Proportion 2 Example computer parts manufacturer disclosed that the defect A computer parts manufacturer disclosed that the defect rate of its product is 0.2. b t k 100 t l f thi ’ A buyer takes 100 parts as a sample from this company’s products and examine if they are defective or not before closing the deal. What is the probability that the proportion of defective parts in a sample is less than or equal to .22? 3 Sample Proportion ach observation in a sample takes two possible value ( Each observation in a sample takes two possible value ( defective, not defective) h b ti i B lli d i bl Each observation is a Bernoulli random variable: X= Number of defective parts(sample) in a sample. What is the distribution of X? The sample statistic of interest is sample proportion Binomial distribution. X P ˆ Is random variable? n P ˆ Yes. When the data are binary (1 or 0, Yes or No), the mean represents proportion of 1 in the data. 4 Sampling distribution of proportion hat is the distribution of if we know X ˆ What is the distribution of if we know population proportion...
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This note was uploaded on 03/01/2011 for the course ECON 220 taught by Professor Tanaka during the Spring '11 term at University of Toronto.
 Spring '11
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