One limitation to Data Sets 1 and 2 is the absence of any information on pennies minted in the years 1980 to 1983, a gap that includes the period when the mean mass of a penny changed from approximately 3.1 g to approximately 2.5 g. A better experimental design would first divide the population of all pennies into separate populations organized by the year of minting. A random sample can then be drawn from each of these populations.
Task 1. Open Data Set 3, using the link on the left, and examine the data on Sheet 1, which provides the mean mass for samples of 10 pennies drawn from the populations of pennies minted in the years 1977 to 1987. Examine the data and explain what it suggests about the change in a US penny's mass over time.
Task 2. Examine the data on Sheet 2, which includes the standard deviations for the data on Sheet 1. Does this additional information alter your conclusions from Task 1? If so, what are your new conclusions?
Task 3. Examine the data on Sheet 3, which provides the mass for all 110 pennies included in this study. Does this additional information confirm (or alter) your conclusions from Tasks 1 and 2? Explain.
After completing these tasks, proceed to the module's summary using the link on the left.