Everyday Research Methods

"Turn off the TV, save your brain?"

Photo: Shutterstock

Pacific Standard does a great job covering social science in the news. Here's a nice example of multiple regression analyses,  in a study they headlined, "Turn off the TV, Save your brain?"

The basic story comes from a large study that found  the amount of TV people watched in their young-adult years was linked to lower cognitive abilities in middle age.

a) So far, this is a simple bivariate correlation. Can you sketch a well-labelled scatterplot of this? Is the relationship positive or negative? 

b) This bivariate correlation apparently has temporal precedence, because the TV variable was measured in young adulthood, before the cognitive abilities (in middle age). Can we make a causal claim now? If not, what third variables might be responsible for this relationship?

Here are some methodological details about the study. You'll see that the story shows the telltale signs of controlling for some of these possible third variables:

The study featured 3,247 people who were recruited from four American cities (Chicago, Minneapolis, Oakland, and Birmingham) in the late 1980s. All were between the ages of 18 and 30 at the study's outset. They were tracked for the next quarter century, with follow-up examinations every two to five years....once every five years, [the participants] indicated "the average number of hours per day (they) spent watching television in the past 12 months."Those who reported watching an average of more than three hours per day during more than two-thirds of their visits were categorized as having a "long-term pattern of high television viewing."

At year 25, the participants took three well-known cognitive tests: the Digit Symbol Substitution Test, which measures speed of mental processing; the Stroop Test, which measures processing speed and attention; and the Rey Auditory Verbal Learning Test, which assesses how well we remember information delivered orally.

Participants who showed a long-term pattern of high TV viewing (approximately 11 percent of the total) scored significantly lower, on average, on [the] cognitive tests...This held true after taking into consideration a range of factors, including age, race, education, alcohol use, and body mass index.

 

c) Based on the description above, you could sketch a multiple regression table depicting this study's results. What would be the criterion variable? What would be the predictor variables? What betas do you think would be significant? Which  betas will be positive? Which will be negative?

d) The description above also tells you how some of the variables were operationalized. For example, how did they operationalize television viewing? How did they operationalize cognitive ability?

e) Even though this study sure feels like it could support a causal claim, it can't. (Remember, no correlational study can definitively support a causal claim.)  That's because even though it has temporal precedence (TV was measured before cognitive ability), and controls for several third variables (including age, race, education, alcohol use, and BMI), they didn't control for all possible third variables. What are some additional third variables that were not controlled for in this study?

 

How should physicians be scheduled? Ethics of a new study.

Why might it be ethical to assign medical residents to 30 hour shifts, in the name of research? Photo: Shutterstock

How many hours in a row should we expect physicians to work in a single shift? Is a 30 hour shift too long? Although residency programs now limit shifts to 16-hours, it used to be the case that doctors (that is, medical residents) could work shifts that were up to 30 hours long. It might seem obvious that 16 hour shifts would be better for both doctors and patients. However, the evidence is  mixed. In addition, some of the participants in a current, ongoing study on this topic are questioning its ethics.

This NPR report (which you can either read or listen t0) introduces the issues and a current study:

The study compares the current rules, which limit first-year residents to working no more than 16 hours without a break, with a more flexible schedule that could allow the young doctors to work up to 30 hours. Researchers will examine whether more mistakes happen on one schedule or the other and whether the residents learn more one way or the other.

First, let's explain why it's interesting to test the differences between 16 and 30 hour shifts:

Longer shifts may actually be safer than shorter shifts, he says, because shorter shifts can lead to more night shifts, which can be even more fatiguing than long shifts. And, Asch says, mistakes often occur when residents have to hand off their patients to other doctors because a rigid schedule forces them to go home. "The new doctor taking care of you never knows you as well as the doctor who was taking care of you before," Asch says. Information handoffs are "like in a relay race, where the baton gets dropped between two runners. And it's known as a critical point where medical errors are common."

Now let's look at how people are talking about the ethics of the study. Here's one comment:

The groups argue the studies put patients and residents at risk. Sleep-deprived residents are more likely to injure themselves while doing procedures such as drawing blood, inserting intravenous lines or suturing wounds, says Michael Carome, who heads the health research group. The accidents could lead to infections with viruses such as hepatitis and HIV, he says. And tired residents tend to get into more car accidents after work.

a) Which of the three Belmont Principles does the statement above mostly address: Respect for Persons? Beneficence? or Justice?

Here's a different ethical concern:

"Patients are not being informed at all, so the patients are completely unwitting subjects of this research," Carome says. "The residents are aware that they are in this trial, but they have no choice to participate unless they want to leave the residency training program."

That's the case for David Harari, a first-year medical resident at the University of Washington Medical Center in Seattle. He knew his hours would be grueling but says he was shocked when he discovered he may have to work 30 hours straight. "I can't see how anyone could work optimally with such little sleep," Harari says. "It's extremely difficult to stay awake, stay alert and function optimally at that level." Harari was offended by the fact he had no choice in the matter. "Being asked to partake in a study in which I never provided informed consent felt extremely unethical and really uncomfortable," Harari says.

b) Which of the three Belmont Principles does the above statement mostly address: Respect for Persons? Beneficence? or Justice?

Now, read how some ethicists are responding to these concerns. The following statements address each of the concerns described above:

Asch also maintains that it isn't practical to get consent from all the doctors and patients in the study. Some independent bioethicists agree.

"They're asking important questions that we need to answer in order to create competent doctors, and I think they're doing it in an ethically sound manner," says Mildred Solomon, who heads the Hastings Center, a bioethics think tank.

Solomon's point is a good example of how we weigh both the costs to participants and the benefits to society, when we are evaluating the beneficence of a study. What do you think?   Read the full NPR report here.