Student researchers investigated whether balsa wood is less elastic aft er it has been immersed in water. They took 44 pieces of balsa wood and randomly assigned half to be immersed in water and the other half not to be. They measured the elasticity by seeing how far (in inches) the piece of wood would project a dime into the air.
a. Identify the observational units, explanatory variable, and response variable in this study.
b. Is this an observational study or an experiment? Explain briefly.
c. Express the appropriate null and alternative hypotheses, in the context of the study, for testing the student researchers’ conjecture that balsa wood is less elastic after it has been immersed in water. The students’ data are in the file Balsawood.
d. Examine graphical displays and summary statistics to compare the elasticity measurements between the two groups. Write a paragraph comparing and contrasting the distributions of elasticity measurements between the two groups.