Question

ch 9* the community intervention trial for smoking cessation asked whether a community-wide advertising campaign would reduce smoking. the researchers located 11 pairs of communities, with each pair similar in location, size, economic status, and so on. one community in each pair was chosen at random to participate in the advertising campaign and the other was not. this is

○ an observational study

○ a matched pair experiment

○ a randomized comparative experiment

Explanation:

1. Observational Study: In an observational study, researchers observe and measure variables without intervening or manipulating any factor. But here, the researchers are assigning (randomly) one community in each pair to the advertising campaign (a treatment), so it's not observational.
2. Matched Pair Experiment: Matched - pair experiments typically involve pairing subjects (or in this case, communities) and then either both subjects in a pair receive different treatments or one is a control. However, in a matched - pair experiment, the pairing is followed by a specific within - pair treatment assignment. But in this case, the key is the random assignment of treatment (advertising campaign) to one of the two similar communities in each pair, and then comparing the two groups (the ones with the campaign and the ones without) across all pairs. This is more characteristic of a randomized comparative experiment.
3. Randomized Comparative Experiment: In a randomized comparative experiment, experimental units (here, communities) are randomly assigned to different treatment groups (here, either receive the advertising campaign or not). The communities are paired based on similar characteristics (location, size, economic status, etc.), and then within each pair, one is randomly assigned to the treatment (campaign) and the other to the control (no campaign). Then we can compare the results between the treatment and control groups across all pairs. This fits the description of the study.

Answer:

a randomized comparative experiment