Everyday Research Methods

Do body cameras affect police complaints?

This Ferguson, MO police officer is wearing a body camera. How would we know if these cameras change behavior? St. Louis Post-Dispatch/Getty Images

This example of a quasi-experiment in the news gives us a lot to think about. The headline reads, "New research shows one big change when cops wear cameras." The story introduced research on seven police precincts in the US and the UK. Here's how the journalist introduced the work:

Cameras worn on police uniforms have been lauded as a possible solution to many of the problems facing officers in the line of duty, from violence against law enforcement to the unnecessary use of force.

The report continues:

Researchers used complaints against police as a proxy for the effect of the cameras, hypothesizing that one major reason for complaints is that cops behaved in a negative, avoidable way. (There are other reasons for complaints, the researchers acknowledge, given the emotionally charged nature of many interactions with police.)

Compared to the previous year when cameras were not worn, complaints across the seven regions fell by 98% over the 12 months of the experiment. The study encompassed nearly 1.5 million officer hours across more than 4,000 shifts.

The news article contained a bar graph, depicting that in the year before the cameras were used, the total number of police complaints was almost 1600. In the year after the cameras were used, the total complaints was fewer than 200.

a) This research used a quasi experimental design. What is the IV? What is the DV? Is the IV an independent groups variable or a within-groups variable? 

b) What kind of design is this--nonequivalent control group posttest only, nonequivalent control group pretest-posttest,  interrupted time series, or nonequivalent control group interrupted time series? 

c) The authors of the report seem convinced that body cameras are the reason for the drop in police complaints seen from one year to the next. But what other possible explanations could there be? What threats to internal validity might apply here, and which could you rule out?  (Consult Table 11.1 or Chapter 13.)

d) In a quasi-experiment, we use both the design and the results to see how close we can get to supporting a causal statement. What changes to this study's design might help you be more convinced that the study can support the claim that "body cameras reduce police complaints"?

 

Thanks to Dr. Carrie Smith (Ole Miss) for this story idea!

Want to get smarter? Brain games won't help....

Playing checkers won't make you smarter in general, but it will make you smarter at checkers!

Photo: Shutterstock / Jaren Jai Wicklun

A variety of research  methods concepts are illustrated in this NPR story, Brain Games Fail a Big Scientific Test. Let's go through the journalist's story, connecting the material to course concepts.

The article starts with the conclusion: Brain games do not make you smarter. 

That's the conclusion of an exhaustive evaluation of the scientific literature on brain training games and programs. It was published Monday in the journal Psychological Science in the Public Interest."

It would be really nice if you could play some games and have it radically change your cognitive abilities," Simons says. "But the studies don't show that on objectively measured real-world outcomes."

a) When the journalist writes, "exhaustive evaluation of the scientific literature," what kind of journal article is he probably describing--an empirical journal article, or a review journal article (Ch 2)?

 

Next, here's the backstory of the journal article in question: 

In October 2014, more than 70 scientists published an open letter objecting to marketing claims made by brain training companies.

Pretty soon, another group, with more than 100 scientists, published a rebuttal saying brain training has a solid scientific base. ...

In an effort to clarify the issue, Simons and six other scientists reviewed more than 130 studies of brain games and other forms of cognitive training. The evaluation included studies of products from industry giant Lumosity....

After combining the results of all the studies (and, notably, after separating the well-conducted studies from the poorly-conducted ones), the researchers concluded that brain games do not make you smarter. Here's a statement of the results: 

There were some good studies, Simons says. And they showed that brain games do help people get better at a specific task. "You can practice, for example, scanning baggage at an airport and looking for a knife," he says. "And you get really, really good at spotting that knife."

But there was less evidence that people got better at related tasks, like spotting other suspicious items, Simons says. And there was no strong evidence that practicing a narrow skill led to overall improvements in memory or thinking.

That's disappointing, Simons says, because "what you want to do is be better able to function at work or at school."

b) This example shows the theory-data cycle in action (Ch. 1). What were the two competing theories this literature review was testing? How do the data support one theory and lead us to reject the other one? 

 

Next, as the researchers collected the studies, they found that some of them were flawed in design: 

The scientists found that "many of the studies did not really adhere to what we think of as the best practices," Simons says.Some of the studies included only a few participants. Others lacked adequate control groups or failed to account for the placebo effect, which causes people to improve on a test simply because they are trying harder or are more confident.

c) How might you design a really strong study to test the effects of a brain training game? What controls would be necessary?

d) What is the downside to including only a few participants in a study? (Ch 10)

 

Suggested Answers

a) This was almost certainly a review journal article.

b) One theory said that brain-training games improve your general intelligence; the other theory said that brain-training games do not improve general intelligence. The review of all the studies combined is consistent with the second theory.

c) Your study designs will vary.

d) The main downside to conducting a study with only a few participants is that small samples can be more likely to produce results that are unusual or extreme, because a few outliers in the data can have an undue influence on the overall pattern. Studies based on larger sample sizes are usually more stable and we can be more confident that they will replicate.