321_09_slides2

321_09_slides2 - Week 1 Review Econ 321 Introduction to...

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Week 1 Review Econ 321 Introduction to Econometrics Econ 321-Stéphanie Lluis 1
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Main Steps in Statistical Analysis Population and Samples Describing data (summary statistics) Inference (CLT) Estimation Hypothesis Testing Econ 321-Stéphanie Lluis 2
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Populations and Samples What is a population? What type of population would you be concerned with in your life? Population parameter What is a sample? Why use a sample rather than populations? Sample statistic to represent the best information about the unknown parameter Econ 321-Stéphanie Lluis 3
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Example for the use of Samples We are interested in a training program which is supposed to improve productivity. It would be very expensive to implement throughout a firm, particularly if it doesn’t work. Instead, we set up an experiment in which we try the program on a sample of employees at a single location (a pilot program) Econ 321-Stéphanie Lluis 4
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Example for the use of Samples We experiment with a pilot program and find that productivity rose by 2% Our problem in using the pilot (sample): if we replicate the pilot throughout the firm is it reasonable to believe that we will get a 2% boost in productivity? could this just be the result of getting a “good” sample (those who happened to respond favorably to the program)? Our core problem in using samples is distinguishing between systematic effects of programs and chance outcomes Econ 321-Stéphanie Lluis 5
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Sampling Variability Samples are affected by randomness Samples are not an exact reproduction of the population 2 samples drawn from a population are unlikely to be identical The sample mean is likely to be different from (but close to) the population mean Econ 321-Stéphanie Lluis 6
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Survey Finds Most Women Unhappy in their Choice of Husbands A popular women’s magazine, in a survey of its subscribers, found that over 90% of them are unhappy in their choice of whom they married. Copies of the survey were mailed to the magazine 100,000’s subscribers. Surveys were returned by 5000 readers. question asked: “If you had to do it again, would you marry the same man?” Conclusion from the news article: Finding Mister right is much harder than anyone realized. Econ 321-Stéphanie Lluis
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This note was uploaded on 07/11/2011 for the course ECON 321 taught by Professor Louis during the Fall '09 term at Waterloo.

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321_09_slides2 - Week 1 Review Econ 321 Introduction to...

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