Scott Alexander announces the winners of the 2019 Adversarial Collaboration Contest and reviews all entries, praising their strengths and noting their impact on readers. Longer summary

Scott Alexander announces the winners of the 2019 Adversarial Collaboration Contest. The winning entry is about calorie restriction and aging by Adrian Liberman and Calvin Reese, with a close second on the ethics of eating meat by David G and Froolow. Scott praises both entries for their different strengths: the calorie restriction piece for its focused approach on a factual question, and the meat ethics piece for its comprehensive review of arguments. He notes that the meat ethics collaboration had a significant impact on readers' eating habits. Scott then briefly reviews the other entries, discussing their strengths and weaknesses. He concludes by explaining the prize distribution and his decision not to run the contest next year, citing various challenges. Shorter summary