Unit 3

A company wants to study the effectiveness of a new pain relief medicine. They recruit 100 volunteers who suffer chronic pain. They assign each subject a number from 1 to 100 and use a random number generator to assign the first 50 subjects selected to the treatment group. The remaining 50 subjects are assigned to the control group. What type of experiment design is this? Choose 1 answer:

Completely randomized

An insurance company wants to study whether offering incentives for preventative care reduces overall health care costs. They select a random sample of 200 of their customers. Half of the smokers are randomly assigned to be offered the incentive, and the other half are assigned to the control group. The same method is used to randomly assign half of the nonsmokers to the treatment group and half to the control group. What type of experiment design is this?

Randomized block

Jerry was reading about a study that looked at the connection between smartphone usage and happiness based on data from approximately 5,000, randomly selected teenagers. The study found that, on average, the teens who spent more time on smartphones were significantly less happy than those who spent less time on smartphones. Jerry concluded that spending more time on smartphones makes teens less happy. Why is Jerry's conclusion not appropriate?

The study was observational, so he shouldn't make a causal conclusion.

A recent study showed that players of a certain video game tend to perform better if they take breaks. The study involved analyzing data from 242,000 matches played by 16,665 players of League of Legends, a popular online game. The data showed that players who took regular breaks, on average, performed better than those who did not. What conclusion can they draw from this study?

There was an association between taking breaks and better performance, but it's not necessarily a causal relationship.

A psychologist thinks that meditation might be a useful tool for patients trying to lose weight. They design an experiment and recruit volunteers who are all interested in losing weight. Half of the subjects (determined at random) will attend weekly guided meditation sessions and receive access to a diet and exercise program. The other half of the subjects will just have access to the diet and exercise program. What is the primary purpose of including a group who doesn't attend meditation sessions?

To serve as a control group for comparison