Quiz 1

This quiz tests how well you learned the material from Class 1 (Introduction and Looking at Data). If you are confident, you can do this in less than ten minutes. To provide time for thinking and checking, we shall allot 20 minutes to complete all questions.

In 1948, Beckman, McCullough, and Crane introduced known amounts (a "standard") of carbon monoxide (CO) in samples of air and performed repeated measurements of each sample. Below are the results for one of the standards.

Microdetermination of carbon monoxide in air (parts per million of CO)

Standard: 25.8

Measurements (partial listing): 26,23,25,25,21,22,27

Source: A. O. Beckman, J. D. McCullough, and R. A. Crane, 1948. Microdetermination of carbon monoxide in air, Analytical Chemistry 20: 674-677, as cited by John Tukey, 1977: Exploratory Data Analysis, page 119.

Construct a stem-and-leaf diagram of these measurements.

Compute the letter summaries and draw a 5-letter summary table.

Draw a boxplot. Show the invisible "fences". How many outliers are there?

Compute these summary statistics: mean, H-spread, MAD. Show your work.

Are these measurements consistent with the standard (the correct value)? List the summary statistics that support your answer.

State, qualitatively, how your answers to #2, #3, and #4 would change if the value of 21 were changed to 210.

Scoring: Start with 100. Subtract 1 for minor errors and trivial mistakes in computation. Subtract 1 for minor calculation or transcription mistakes, 5 for major blunders, 10 for completely wrong answers. The passing score is 96.

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