I should stay at the start - dogs are amazing, we don't deserve their love BUT Facts are still importantpic.twitter.com/UTslm6eU9g
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The researchers did what's know as a systematic review and meta-analysis, looking at all of the studies on dog ownership and health that they could findpic.twitter.com/d6M7e9Xpzu
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They then pooled the numbers from all of these studies into a meta-analysis, which showed that owning a dog was associated with a 24% decreased risk of death, overallpic.twitter.com/J72bvsJGgQ
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So why am I not going out to corral every dog I can find? Well, there were a few significant issues with the studypic.twitter.com/Jjx2YE3zBX
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First up, we have what's known as statistical heterogeneity Basically, this means that the studies that the researchers found and analyzed together were very different, making the analysis less reliablepic.twitter.com/hJwm6VVoLV
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How different were these studies? Well, a commonly-used measure to assess heterogeneity is the I^2 statistic. A value between 0-50% is considered "low" This study found I^2 between 96-98% (except for one subgroup analysis)pic.twitter.com/h078Q4zngn
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This makes sense, because the studies that they found were VERY DIFFERENT For example, one study looked at ~everyone in Sweden~, while another looked only at elderly women with hypertensionpic.twitter.com/ar19xXbniu
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But that wasn't the biggest issue The biggest issue was that this piece of research didn't look at confounding factors At allpic.twitter.com/z7jrTWYspY
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Now, I bang on about observational research and the problems with causality, but that's usually in well-controlled studies where residual confounding might potentially be an issue
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Here, we have a piece of research that didn't control for any factors other than dog ownership ~at all~ It's not hard to see how this might make the results a bit problematicpic.twitter.com/9ZY2Jp6csH
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Essentially, it means that this study just looked at a simple association Dog owners die a bit less than non-owners That's it!
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Dog owners are often very different to non-owners in important ways From the Swedish study I mentioned above, owners were more educated, married more often, more likely to have kids, etcpic.twitter.com/LmYkqrlFuE
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What this means is that there are literally hundreds of explanations for dog owners being more healthy than non-owners that have nothing to do with the dogs Funnily enough, that's something that the authors noted in the studypic.twitter.com/BWzTi99vJs
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Basically, healthy people might be more likely to buy dogs Thus, dog owners die less Association rather than causation
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And the mechanisms of dogs saving our lives are a bit flimsy. Some minor reductions in blood pressure =/= lifesaving
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So...puppies probably aren't saving our lives They're still great tho, you should definitely get one Adopt, don't shop!pic.twitter.com/n0a6UOHvZf
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