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Problem 1: You are trying to decide if students who sleep more have better grades.A survey was created online and

send it to friends, asking them to share it with any other students that they know. The survey asks respondents for two numbers: an approximate number of hours they sleep during a typical night and their GPA. The scatterplot, showed a trend that typically, people with less sleep have lower grades and people with more sleep have higher grades.

Identify the explanatory and response variables.

What type of sampling method is being used? Would this method be effective or ineffective at producing a reasonable sample for answering your research question?

Can we establish a causal relationship between the explanatory and response variables? Why or why not?



Problem 2: A psychology student wants to determine the effects of exercise on mental health. To conduct her study, she randomly selects ten individuals for three different age groups: 18-30, 31-40, and 41-55. She randomly instructs half of the subjects from each age group to exercise three times a week and tells the rest not to exercise. She conducts a mental health exam before and after the study and compares the results. Answer the following questions:

Is this an observational study or an experiment? How can you tell?

What are the treatment and control groups, if any?

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

Does this study make use of blinding? Explain.

Can this study be used to establish a causal relationship between exercise and mental health? Explain.

Top Answer

The sample method is stratified sampling because there is two strata. The explanatory is hours of sleep the response is GPA.... View the full answer

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