Question

a research team is investigating whether adding vanilla to a smoothie drink improves the taste. over several days and times of day, a researcher fills 20 red and 20 blue cups with the same brand of smoothie drink, then adds a dash of vanilla to each of the 20 blue cups. a second researcher, who does not know which cups have the added vanilla, takes the cups to a nearby grocery store. willing customers are given one blue cup and one red cup to drink, and each customer keeps a record of the cup color and the associated taste score. at the end of the study, the first researcher will compare the taste scores between the two vanilla statuses (with vanilla and without vanilla). (a) first choose whether the procedure described above is an observational study or a designed experiment. then further categorize the procedure by choosing the correct type of observational study or designed experiment. observational study designed experiment prospective retrospective double - blind completely randomized (b) which one of the following best describes the explanatory (independent) and response (dependent) variables? the explanatory variable is the taste score and the response variable is the vanilla status.

Explanation:

(a) In this study, the researchers are actively manipulating the presence or absence of vanilla in the smoothie (treatment), and observing the taste scores given by customers. This is a designed experiment. Since neither the customers (who don't know which cup has vanilla) nor the second - researcher (who doesn't know which cup has vanilla) are aware of the treatment assignment, it is a double - blind experiment.
(b) The explanatory variable is the variable that the researchers manipulate or change. Here, it is the presence or absence of vanilla in the smoothie (vanilla status). The response variable is what is being measured as a result of the change in the explanatory variable, which is the taste score given by the customers.

Answer:

(a) Double - blind, Designed experiment
(b) Explanatory variable: Vanilla status; Response variable: Taste score