Investigators planted pine seedlings in the greenhouse in either full light OS light condensed to 5% of normal by shade cloth to estimate how well these pines grow in shade. At the end of the study, they dried the young trees and weighed them.
I. Determine the population?
II. What is the sample?
III. Is this study observational or experimental?
IV. What are the variables?
V. For each of those variables, what level of measurement (nominal, ordinal, interval, or ratio) was used to obtain data from these variables?