The data referenced in this project is LightatNight8weeks. If you are unable to answer all questions, I

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The data referenced in this project is LightatNight8weeks. If you are unable to answer all questions, I will post another set separately. Please Help (Stat Key is also good to use for this assignment) I attached an excel spreadsheet for this project as well (LightatNight8weeks.csv)

In Data 4.1 on page 000, we examine a study in which mice were randomly assigned to either a normal light/dark cycle or to have a light on around the clock. According to the paper describing that study, “The global increase in the prevalence of obesity and metabolic disorders coincides with the increase of exposure to light at night.” The study is examining whether light at night plays a causal role in the obesity epidemic. In Data 4.1, we examine the effect of the different light conditions on body mass gain after three weeks. In fact, the actual experiment lasted 8 weeks and examined many additional variables.1 The data referenced here are available in LightatNight8weeks. Some of the variables are summarized in the following table.

1. What are the cases? What is the explanatory variable? Is this a randomized experiment or an observational study?

2. What is the mean body mass gain for all the mice in this dataset? What is the five number summary? Show a graph of the body mass gains in the sample. Do there appear to be any outliers? Find and interpret a 95% confidence interval for mean body mass gain.

3. The primary question in the study was whether having a light on at night causes greater average body mass gain. Give side-by side boxplots comparing body mass gain for the two groups. Does having a light on at night appear to increase body mass gain in mice?

4. Conduct a hypothesis test to see if the data provide evidence that mean body mass gain is higher for mice with a light on at night. Show all details of the test. If the results are significant, can we conclude that there is a causal association? Why or why not?

5. To examine how large is the effect on body mass gain of having a light on at night, give a 99% confidence interval for the difference in mean body mass gain between mice with a light on at night and mice with darkness at night. Interpret the interval in context.

6. Perhaps the difference in weight gain between the two groups was affected by a difference in food consumption. Conduct a hypothesis test for a difference in mean consumption between the two groups. Is there evidence of a significant difference in average food consumption between the two groups?

7. Perhaps the difference in weight gain between the two groups was affected by a difference in activity level. Conduct a hypothesis test for a difference in mean activity level between the two groups. Is there evidence of a significant difference in average activity level between the two groups?

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