Quiz 1 (retest 1)

Time: 20 minutes..

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: 90.5

Measurements: 95, 96, 92, 102, 103, 93, 101, 92, 95, 90

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.

  1. Construct a stem-and-leaf diagram of these measurements.
  2. Compute the letter summaries and draw a 5-letter summary table.
  3. Draw a boxplot.  Show the invisible "fences".  How many outliers are there?
  4. Compute these summary statistics: H-spread, MAD, 20% trimmed mean.  Show your work.
  5. Are these measurements consistent with the standard (the correct value)?  List the summary statistics that support your answer.
  6. State, qualitatively, how your answers to #2, #3, and #4 would change if 100 were subtracted from each value above 100 (Excel used to do things like this when exporting spreadsheets)..
    7.

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 95.

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