The Blackwell's

Blackwell’s theorem, in decision theory, establishes that if one decision-making process (or 'information structure') provides more accurate or informative data than another, then any decision based on this better information will not be worse—in fact, it can only improve the expected outcome. Think of it as a formal way to compare the value of different information sources: more informative data leads to better decisions and higher expected rewards, ensuring that acquiring better information is always beneficial for decision-makers.