Beware of the bias!

When you hear reports of research studies with splashy titles, sometimes you have to think twice (and definitely read more than just the headline!)

For example – the most recent splashy headline that’s been all over the news is about Chronic Traumatic Encephalopathy (CTE), the degenerative brain disease that has been linked to concussions. Check out the New York Times article entitled “110 Brains”, detailing that “a neuropathologist has examined the brains of 111 NFL players — and 110 were found to have CTE.”  This article is based on a study published in JAMA. This would seem to imply that 99% of football players suffer from CTE.  Is this true?  Should football be banned since players are almost guaranteed to get CTE? Well, slow down there a moment before burning all your prized football jerseys. Let’s do a brief talk about bias.

Bias is a preconceived opinion about something or someone, it may cause you to lean in a certain direction when considering information. Basically, a prejudice. A bias can be favorable or unfavorable.  The specific bias in this article is called selection bias. Selection bias (sometimes called sampling bias) is the prejudice introduced by the selection of individuals, groups or data for analysis in such a way that proper randomization is not achieved, thereby ensuring that the sample of subjects obtained is not representative of the population intended to be studied.  In this article, the selection bias is that all the brains that were donated to be examined were donated because there was thought to be something wrong.  This was a convenience sample introduced by concerned family members, NOT a random sampling of brains of people who have ever played professional football. Are these results generalizable – can they be applied to all football players?  Probably not. Now to be fair, this articles does discuss its own selection bias about midway through, but how many people actually read the article that far?  To be honest, I have had this exact same conversation with other health care providers, who didn’t read much beyond the headline before determining that they would never allow another patient to participate in contact sports. I’ve also had this exact same conversation with parents debating whether or not I should sign their teen’s sports participation form.

Now, compare the New York Times article about CTE in football players with this article from Yahoo News. Sure, the New York Times article grabs your attention, but the Yahoo Sports article is more thorough and accurate. It looks at a bunch of different research articles. It discusses quality of life of former football players prior to death (since CTE can only be diagnosed via autopsy after death, and we aren’t exactly sure how it impacts the living). This article also delves into the topic of “correlation does not equal causation.”  Just because two things seem to be related, you can’t always prove a cause-and-effect relationship – did Junior Seau commit suicide because of effects of CTE, or were they unrelated? We will never be able to prove it one way or the other.

We have written several blogs about concussions and football, so I’m not going to rehash that now. I just want to make sure that you readers are a responsible consumer of information. Moral of the story – when you see a splashy headline, make sure to read the whole article and look for any bias.  That way, you can make up your own mind.

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