It appears that the value relevance of reported earnings, as measured by R2 or ERC, is low,

Question:

It appears that the value relevance of reported earnings, as measured by R2 or ERC, is low, and possibly falling over time. Use single- person decision theory to explain why the value relevance of reported earnings can be measured by R2 or ERC. Is it possible for an abnormal share return to increase but R2 and ERC to fall? Explain.