Key - Exam 1 A - 2009 (1)

# Key - Exam 1 A - 2009 (1) - Name: Exam 1A Key Lab Exam 1A...

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Lab Exam 1A – Univariate and Bivariate Statistics The spreadsheet Exam 1A – 2009 contains a sample of used 2004 Honda Accord prices and related data. Before you do anything, save your file to the folder named “Dropbox” as : Exam 1A lastname- firstname.xlsx . Now, complete the exercises below using these data. 1. Accord prices – univariate distribution. (5) a. First, sort the data by the variable Price in ascending order (smallest to largest prices). (9) b. Determine the means , medians , and standard deviations for the variables price and mileage using the Excel functions . (6) c. What do these means and standard deviations represent? Explain . The means and standard deviations are our best guesses about the true population parameter values . We refer to the formulas as estimators ; we refer to the numeric values we obtain after plugging in sample data as estimates . (4) d. Interpret the mean price you’ve calculated. On average a used 2004 Honda Accord will be priced at \$21,863. So, our estimate tells us that if we looked at many different Honda Accords, their prices would be \$21,863, on average. (This sample mean is our best guess about the true population mean .) (4) e. Interpret the standard deviation of price you’ve calculated. On average, used 2004 Honda Accords are priced within \$2,014.90 of the mean prices of \$21,863. So if we looked at many different Honda Accords, on average their prices would fall within \$2,014.90 of the mean \$21,863. (6) f. Create a 90% confidence interval estimate of the unknown population mean used 2004 Honda Accord price.

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## This note was uploaded on 12/08/2011 for the course ECON 312 taught by Professor Daniellass during the Winter '10 term at UMass (Amherst).

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Key - Exam 1 A - 2009 (1) - Name: Exam 1A Key Lab Exam 1A...

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