Part 1: The benefits of gardening

Can time spent gardening ease anxiety? A total of 32 women between the ages of 26 and 49 years of age were recruited to participate in a study. The researchers randomly assigned half of the women to attend gardening classes twice week for four weeks. The other half of the women were randomly assigned to attend art-making classes twice a week for four weeks. Prior to the start of the study, the women completed an assessment that measured their level of anxiety. After attending classes for four weeks, the women again completed the same assessment. When looking at changes in anxiety from before the study to after the study, the researchers noted more improvement in anxiety among the women who attended gardening classes compared to the women attending art-making classes.

1. Would the study described above be considered an experiment or an observational study? Please explain.

2. Regardless of whether a study is an experiment or an observational study, we can classify particular variables involved in the study as being response variables or explanatory variables. Within the context of this study, type of course (either gardening or art-making) would be considered a(n) _______________________ variable, whereas change in anxiety level

would be considered a(n) ________________________ variable.

3. The researchers recruited participants for their study by distributing flyers about the study throughout the University of Florida Gainesville campus. This means the researchers have what is considered to be a ______________________ sample.

4. The researchers randomly assigned the women in their study to complete either gardening classes or art-making classes. What does it mean if a study uses random assignment, and why is that important?

5. Based on the results of this study, do you think it should be recommended that people who are very anxious should take up gardening? Why or why not?

Part 2: Is Facebook harmful to your GPA?

In 2010, an article was published about the use of Facebook and how it might impact academic performance. The article presented the results of a survey of n = 219 college students from one large, public Midwestern university. The students were asked to indicate whether or not they use Facebook. They were also asked to report their GPA. The researchers found that those students who used Facebook had lower GPAs than those students who did not use Facebook.

6. Would you consider the study described above to be an experiment or an observational study? Please explain.

7. What is the explanatory variable in this study?

8. What is the response variable in this study?

9. Suppose you learn that the researchers recruited participants for their study by visiting scheduled classes and asking students if they would like to take part in a study about social media. The students who said "yes" completed and returned the survey instrument. What type of sample do we have here? Please explain.

10. In this study, students self-reported whether or not they used Facebook. They also self-reported their GPA. Why might this be a problem?

11. A critic of this study says that it would be impossible to conclude that using Facebook causes a student to have a lower GPA because of the many lurking variables that were not controlled for in this study. Explain what it means when we say that "many lurking variables" were not controlled for.

12. True or False. If the students who participated in this study did not know that the study was about the relationship between Facebook use and GPA, we'd call this a double-blind study.