3 Test Part I - Multiple Choice Circle the letter corresponding to the best answer choice. (1.5 pts each question) 1. What is the purpose of the random assignment of treatments to subjects in an experiment? (A) To create roughly equivalent groups before treatments are administered. (B) To prevent certain groups in the population from being systematically excluded in the experiment. (C) To reduce bias in the selection of the subjects to be included in the experiment. (D) To eliminate the need for blinding in an experiment. 2. A random number generator is used to select 12 students from a large statistics class to rate a statistics video. The 12 students selected are (A) the population C) a census (B) a simple random sample of the class (D) a voluntary response sample Use the following scenario for questions 3 and 4. The next two questions concern this situation: A random sample survey interviewed 3,800 U.S. adults nationwide by telephone. One question asked was whether they agreed with this statement: "Some people say we should have a third major political party in this country in addition to the Democrats and Republicans." In this sample, 53% of the people asked responded, "Yes, we should have a third political party." 3. The population for this sample survey appears to be (A) all registered voters. (B) all adult residents of the U.S. (C) the 3,800 people who were interviewed. (D) people who think we should have a third political party. 4. The news article that reports the poll results says, "The margin of error is plus or minus two percentage points." This means that (A) we can be absolutely certain that between 51% and 55% of all adult Americans think we should have a third party. (B) we expect that exactly 53% of all adult Americans think we should have a third party. C) we expect that between 51% and 55% of all adult Americans think we should have a third party. (D) we expect that between 51% and 55% of the 3,800 people interviewed think we should have a third party. 5. A recent study showed that teenagers who had night-lights in their rooms as babies are more likely to suffer from myopia (near sightedness) than teenagers who had not used night-lights. However, genetic factors are known to play a role, and near-sighted parents are more likely to install a night light in their children's room. This makes it hard to tell if the night light caused the myopia. This is an example of (B) the placebo effect. (A) double-blinding. (D) an explanatory variable. C) a confounding variable. 6. Which of the following is a valid statistical question? (A) How many people voted in the last school board election? (B) How many points were scored by the New England Patriots during the 2014-15 regular NFL season? (C) How long will you be in line when your get lunch from the cafeteria? (D) How tall is Mount Everest