Question

A researcher is interested in the effects of exercise on mental health and he proposes the following study: Collect a sufficiently large sample using stratified random sampling to ensure representative proportions of 18-30, 31-40 and 41-55 year olds from the population. Next, randomly assign half the subjects from each age group to exercise twice a week, and instruct the rest not to exercise. Conduct a mental health exam at the beginning and at the end of the study, and compare the results. a) Is this an observational study or an experiment? This is an observational study. This is an experiment. b) Does this study make use of blocking? If so, what is the blocking variable? Yes, the blocking variable is their mental health. O Yes, the blocking variable is age. Yes, the blocking variable is exercise. No, there is no blocking variable. c) Can the results of the study be used to establish a causal relationship between exercise and mental health? Yes, since the sample size is large enough. Yes, since there is random selection from the population. Yes, since there is random assignment of treatment and control groups. c) Can the results of the study be used to establish a causal relationship be mental health? Yes, since the sample size is large enough. Yes, since there is random selection from the population. O Yes, since there is random assignment of treatment and control groups. No, since the sample size is too small. d) Can the conclusions be generalized to the population at large? O Yes, conclusions can be generalized for adults aged 18-55. O No, since the sample size is too small. No conclusions can be made since adults older than 55 were not included. Yes, since the sample size is large enough.

Answer 1

i listed them below btw

Step-by-step explanation:

a) Is this an observational study or an experiment?

This is an experiment. The researcher is actively intervening by randomly assigning subjects to different groups (exercise and no exercise) to study the effects of exercise on mental health.

b) Does this study make use of blocking? If so, what is the blocking variable?

Yes, the study makes use of blocking. The blocking variable is age. The researcher ensures representative proportions of different age groups (18-30, 31-40, and 41-55) using stratified random sampling.

c) Can the results of the study be used to establish a causal relationship between exercise and mental health?

Yes, since there is a random assignment of treatment and control groups. Randomly assigning participants to exercise or no exercise helps minimize the impact of confounding variables, making it more likely to establish a causal relationship between exercise and mental health.

d) Can the conclusions be generalized to the population at large?

Yes, conclusions can be generalized for adults aged 18-55. The study used stratified random sampling to ensure representative proportions of different age groups within this range. However, the conclusions cannot be generalized to adults older than 55 since they were not included in the study.