Two popular over-the-counter antacids are compared to determine which brand is preferred. Three hundred subjects are randomly selected then divided into two groups of 150 each, and given one of the two antacids. The researchers in the study were unaware of which antacid was administered at any time during the study.
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?