Correlation is not causation.
A new study by the L.A. Gay & Lesbian Center and UCLA suggests that men who have sex with men and use hookup apps like Grindr are significantly more likely to have gonorrhea and chlamydia than men who have sex with men but do not use such apps. But before you panic and delete Grindr from your phone lest it give you an STI, let’s look at what the study does and does not actually show.
Researchers and science writers—the ones who know what they’re doing, that is—often kvetch about “correlation versus causation,” a common misunderstanding about statistics in research. Causation means that one thing has been shown in an experiment to cause another (probably).
For instance, suppose I have two groups of identical mice and I treat them exactly the same except that one group gets fed normal mouse food for a week and the other gets fed nothing but Nutella for a week. I have now performed an experiment. If at the end of the experiment the Nutella group is bigger and more active than the other group, it’s probably reasonable to assume that the Nutella caused the mice to grow larger and become more active. (Don’t actually do this.)
Correlation refers to a statistical test that is used to analyze data and determine whether or not there is a relationship between the data. For instance, suppose I’m studying a group of children over a long period of time. Once a year, I ask the children a series of questions about video games—which ones they like, how much violence there is in the games, how much they like shooting or fighting other characters in the games, and so on.
I also ask their parents to report their children’s aggressive behavior—whether/how often they’ve gotten in a physical fight with another child, how often they take anger out on toys or other objects, and so on. Suppose I determine that the children who play the most violent video games also get into the most fights. I have found a correlation between exposure to video game violence and actual violent behavior, but I haven’t proven that one causes the other. Just that they tend to go together.
In this particular study, the researchers have determined that this particular sample of men who have sex with men (a designation used to focus on sexual behavior rather than labels like “gay” or “bisexual”) was 25 percent more likely to have gonorrhea and 37 percent more likely to have chlamydia if they used hookup apps than if they didn’t. (No differences were found for syphilis, and all the participants self-identified as HIV-negative.)
The researchers were specifically interested in what they called geosocial networking applications (GSN apps), which are apps that broadcast a user’s location and allow users to find each other if they’re physically nearby. These apps allow men to find hookup partners anonymously, without needing to out themselves to in-person communities or groups.
At Slate, J. Bryan Lowder urges caution in interpreting the study’s findings. Lowder notes that the men in the sample live in West Hollywood and Long Beach, which might be unique in terms of population density (not to mention cultural norms). Furthermore, the authors of the study themselves caution that the data comes from an organization that treats STIs, so the sample might be skewed towards men with riskier sexual behavior (although that should in theory apply to the men who don’t use GSN apps as well as the ones who do). Lowder adds:
While many are no doubt interpreting this study as a kind of scold against digitally assisted promiscuity, it’s worth noting that the authors are far more interested in using these apps as a means of promoting sexual health rather than in chastising anyone: ‘Given that mobile technologies allow for a variety of functions beyond locating anonymous sexual partners, the feasibility and effectiveness of various culturally competent, electronic applications that emphasize wellness through testing promotion, prevention and education should be explored.’
However, careless headline writers frequently mix up correlation and causation, spreading misinformation and stigma. Despite Lowder’s balanced take on the study, the headline of his own piece reads, rather alarmingly, “Study Suggests Grindr-Like Apps Increase Likelihood of Sexually Transmitted Infections.” This wording implies that using such apps increases an individual’s likelihood of contracting an STI, not that, in general, people who use such apps are also more likely to have an STI. It’s a fine distinction, but an important one.
Another important distinction is whether the participants contracted the STIs during the course of the study (while using GSN apps) or just happened to have them at the time that the data was collected. Here Lowder’s article is also unclear: “Specifically, geo-social app users were 25 percent more likely than their bar hopping comrades to contract gonorrhea, and 37 percent more likely to have picked up chlamydia.” And an article about the study at Advocate is headlined, “STUDY: Smartphone Hookup App Users More Likely To Contract Sexually Transmitted Infections.”
However, the actual study notes that the participants were tested for STIs at the same time as they were asked about their sexual behavior, including the use of GSN apps. This means that they did not necessarily contract the STIs while using the GSN apps, or after having used them. The infections could have preceded the participants’ use of the apps.
This is important because it can help untangle the question of why this correlation exists, besides the obvious hypothesis that using GSN apps can actually cause people to contract STIs at higher rates than other ways of meeting sexual partners. Perhaps people who already have STIs are more interested in using the apps because of the anonymity—it’s much less scary to tell a random person you’ll never meet again that you have an STI and need to use a condom than it is to tell someone who’s embedded in your social network. Or, on the more cynical side of things, people might feel less guilty about not disclosing an STI to a random app hookup than someone they’ve met in a more conventional way.
Or, maybe people who are attracted to “wild” and “risky” sexual situations are more likely to have STIs and more likely to use GSN apps. The common factor could be impulsivity or recklessness.
These fine lines matter not only because it’s important to understand what the evidence actually does and doesn’t show, but because STIs are still stigmatized far more than non-sexually transmitted infections of similar severity. The fact that they’re spread via sexual contact makes them uncomfortable, even scary, to discuss candidly. But STIs are common and they’re not going away anytime soon. Journalists who cover research about them should take care to represent the findings accurately to avoid potentially increasing the stigma that people with STIs face, especially people whose sexual behavior is already considered suspect by default.
Miri Mogilevsky is a social work student who loves feminism, politics, New York City, and asking people about their feelings. She writes a blog called Brute Reason, tweets @sondosia, and rants on Tumblr.
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