A dietary researcher studying grocery expenses is interested in the possible effect that having a vegetarian diet has on a single (unmarried) person's monthly grocery bill. To investigate, the researcher conducts an observational study by contacting a sample of 300 single adults who are homeowners. The researcher gathers the following information from each participant: dietary habits (vegetarian or meat-eater), monthly grocery bill, yearly income and education level. From the data, the researcher creates two groups: vegetarians and meat-eaters. Then he compares the average monthly grocery bill between the two groups. (a) Why might the researcher have chosen to perform an observational study (by gathering information about participants' current behaviors) and not a randomized experiment (by assigning participants to either the vegetarian or meat-eating X ? group at random)? Choose the best answer from the choices below. For a randomized experiment to be performed, the researcher must ask people in the population to volunteer to take part. This would mean that there would not be any chance to include vegetarians in the sample. O A randomized experiment should never be performed when it is possible to perform an observational study. When groups are randomly assigned, the researcher cannot control the types of participants in each group, making the results of a randomized experiment unreliable. In a randomized experiment, it could be that some participants who do not eat meat would be assigned to the meat-eating group, meaning that they'd be forced to eat meat. It would not be ethical to force people to eat meat. (b) The variable home ownership is not a possible confounder in this study. Choose the best reason why. O A variable is a confounder if, based on its value, it prohibits some members of the sample from participating in the study. For this study, there were no participants in the sample who did not own a home. So, each person in the sample could participate in the study. A variable is a confounder if its effect on the outcome cannot be distinguished from the effect on the outcome from different treatments. (In our context, the outcome is the monthly grocery bill, and the treatments are being a vegetarian and being a meat-eater.) In this study, both treatment groups (vegetarian and meat-eater) were similarly comprised of only participants who owned a home. Thus, the researcher designed the study so that whether or not a participant owns a home would not be a confounder. (c) The variable education level is a noccible confounder in this study Chance the hack reacon why Submit Assignme Continue MacBook Air 20 888 DII DD F9 F11 F1 F3 F5 F6 F7 F10 F2 F4 &(c) The variable education level is a possible confounder in this study. Choose the best reason why. A variable is a confounder if its effect on the outcome cannot be distinguished from the effect on the outcome from different treatments. (In our context, the outcome is the monthly grocery bill, and the treatments are being a vegetarian and being a meat-eater.) There is already a noticeable difference between the two groups of participants In terms of dietary habits. It's possible the participants in the vegetarian group differ from the participants in the meat-eating group in other characteristics, such as education level, making it difficult to determine which variable is affecting the monthly grocery bill. O A variable is a confounder if, based on its value, it prohibits some members of the sample from participating in the study. For this study, there may be some people who did not graduate from high school making it not possible for them to participate in the study. (d) Suppose the researcher is interested in reducing the effect that differences in education level might have on monthly grocery bills between the vegetarian and meat-eating groups. What is a reasonable approach for the researcher to take? Choose the best answer from the choices below. The researcher could aim to select a vegetarian and then find a meat-eater who has a higher education level than the vegetarian. She could continue to create pairs of participants in this way, such that each pair contained one vegetarian and one meat-eater and such that the meat-eating participant in the pair always has a higher education level. Then she could compare the average monthly grocery bills between the vegetarian group (having a lower education level) and the meat-eating group (having a higher education level). The researcher could divide the participants in the vegetarian group into two groups: those with at least some education and those without any college education. She would divide the meat-eating participants in the same way. Then the average monthly grocery bill could be compared between the vegetarians and meat-eaters, by education level. The researcher could increase the sample size. Increasing the sample size helps to reduce the effect that confounding variables have on the outcome of the study. A sample size of at least 1000 participants is recommended to control for unwanted variation in a study. Submit Assignment Continue MacBook Air DD 20 888 F10 F6 F9 esc E3 F4 F5 % & @ # 3 4 6 8 O 5 2