Refer to the study in Exercises 1 and 2, comparing the percentage of smokers who quit using a nicotine patch and a placebo patch. Refer to the definition of statistics given on page 1, and explain how it applies to this study.

Exercise  1
Refer to the study in Exercise 2, in which there was a statistically significant difference in the percentage of smokers who quit using a nicotine patch and a placebo patch. Now read the two cautions in the "moral of the story" for Case Study 1.7. Discuss each of them in the context of this study.

Exercise 2
Dr. Richard Hurt and his colleagues (Hurt et al., 1994) randomly assigned volunteers wanting to quit smoking to wear either a nicotine patch or a placebo patch to determine whether wearing a nicotine patch improves the chance of quitting. After 8 weeks of use, 46% of those wearing the nicotine patch but only 20% of those wearing the placebo patch had quit smoking.
a. Was this a randomized experiment or an observational study?

b. The difference in the percentage of participants who quit (20% versus 46%) was statistically significant. What conclusion can be made on the basis of this study?

c. Why was it advisable to assign some of the participants to wear a placebo patch?

Case Study
Does the Internet Increase Loneliness and Depression?

It was big news. Researchers at Carnegie Mellon University had found that "greater use of the Internet was associated with declines in participants' communication with family members in the household, declines in size of their social circle, and increases in their depression and loneliness" (Kraut et al., 1998, p. 1017). An article in the New York Times reporting on this study was titled "Sad, lonely world discovered in cyberspace" (Harmon, 1998). The study included 169 individuals in 73 households in Pittsburgh, Pennsylvania, who were given free computers and Internet service in 1995, when the Internet was still relatively new. The participants answered a series of questions at the beginning of the study and either 1 or 2 years later, measuring social contacts, stress, loneliness, and depression.

The New York Times reported:
In the first concentrated study of the social and psychological effects of Internet use at home, researchers at Carnegie Mellon University have found that people who spend even a few hours a week online have higher levels of depression and loneliness than they would if they used the computer network less frequently. . . . it raises troubling questions about the nature of "virtual" communication and the disembodied relationships that are often formed in cyberspace.

Given these dire reports, one would think that using the Internet for a few hours a week is devastating to one's mental health. But a closer look at the findings reveals that the changes were actually quite small, though statistically significant. Internet use averaged 2.43 hours per week for participants. The number of people in the participants' "local social network" de creased from an average of 23.94 people to an average of 22.90 people, hardly a noticeable loss.

On a scale from 1 to 5, self-reported loneliness decreased from an average of 1.99 to 1.89 (lower scores indicate greater loneliness). And on a scale from 0 to 3, self-reported depression dropped from an average of .73 to an average of .62 (lower scores indicate higher depression). The New York Times did report the magnitude of some of the changes, noting for instance that "one hour a week on the Internet was associated, on average, with an increase of .03, or 1% on the depression scale." But the attention the research received masked the fact that the impact of Internet use on depression, loneliness, and social contact was actually quite small, and thus may not have been of much practical significance.

As a follow-up to this study, in July 2001, USA Today (Elias, 2001) reported that in continued research, the bad effects had mostly disappeared. The article, titled "Web use not always a downer: Study disputes link to depression," began with the statement "Using the Internet at home doesn't make people more depressed and lonely after all." However, the article noted that the lead researcher, Robert Kraut of Carnegie Mellon University, believes that the earlier findings were correct but that "the Net has become a more social place since the study began in 1995." His explanation for the change in findings is that "either the Internet has changed, or people have learned to use it more constructively, or both." Research on this topic continues to develop.

A study released in February 2010 (Morrison and Gore, 2010) identified 18 "Internet addicted" individuals out of 1319 study participants. They found that the Internet addicts scored in the "moderately-to-severely depressed range" on a test called the Beck Depression Inventory, while an equivalent group of non-addicts scored "firmly in the non-depressed range." As the authors point out, it is not clear whether Internet use causes depression, depression causes more Internet use, or some other factors lead to abnormal scores in both for some people.

Moral of the Story: A statistically significant finding does not necessarily have practical significance or importance. When a study reports a statistically significant finding, find out the magnitude of the relationship or difference.

A secondary moral to this story is that the implied direction of cause and effect may be wrong. In this case, it could be that people who were more lonely and depressed were more prone to using the Internet. And remember that, as the follow-up research makes clear, "truth" doesn't necessarily remain fixed across time. Any study should be viewed in the context of society at the time it was done.