Blackwell's theorem

Blackwell's theorem addresses how to compare information sources. It states that one source is at least as good as another for decision-making if, whenever you use the first source to inform your choices, your results are at least as good as if you used the second source, regardless of the specific decision problem. In essence, it provides a way to determine which information source is more informative: if you can process the first source's data to replicate or improve upon the second source's insights, then the first is considered more informative. This helps in selecting the best information to make optimal decisions.