Well most people who drink diet soda are fat. Why else would you drink it?

They say correlation does not imply causation, but have you noticed how often sentences with the word "correlation" also have the word "causation"?

When I drink Diet Coke, I choose to drink it to avoid ingesting 40g+ of sugar. And I also prefer its taste to compared to sugar. And I am the opposite of fat.

There's a reason that students are taught on day 1 of Statistics 101 that observational studies can only establish correlation, NOT causation. Otherwise we might as well just admit that cancer causes smoking.

It's one of the most pervasive and blatant errors seen in the news and social media.