Journalistic malpractice – the diet soda study

Sitting in Israel writing this blog post, drinking a diet coke, and wondering what they were thinking. You have read the headline, or heard it on TV or the radio – diet sodas cause dementia and strokes. That was the headline, but any careful analysis of the study suggests that they did not PROVE anything. Aaron Carroll – the Incidental Economist – has a great analysis – They did not prove that diet soda causes Alzheimer’s Disease. THEY DID NOT! For a profane, but funny take – DIET COKE WON’T CAUSE STROKE, BUT READING SENSATIONALISTIC HEADLINES MIGHT The problems in short: Too many comparisons without adjustments.  When you do multiple comparisons in an observational study, you must adjust your p value for the multiple comparisons.  I learned Bonferroni’s correction (divide p by the number of comparisons. No such correction occurred in this study. All retrospective observational analyses should raise question marks. The headline writers know neither medicine nor statistics.  The headlines scare many people reading only the headlines. This story is really a non-story. Vinay Prasad said it best in a tweet: Diet soda study, Adjust for the 90+ comparisons you provide, and a significant p is 0.0005 Nothing here is significant. This is BAD paper The diet coke tasted great.
Source: DB's Medical Rants - Category: Internal Medicine Authors: Tags: Medical Rants Source Type: blogs