A researcher wants to determine if teenage drivers of red automobiles are more likely to run a red light than automobiles of any other color. She stands at a busy intersection and records the colors of automobiles which run red lights.

I. What is the population?
II. What is the sample?
III. Is the study observational or experimental? Justify your answer.
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?