A researcher finds evidence of a security price reaction to an item of accounting information

during a narrow window of three days surrounding the release date of this information in

which no other significant events affected the firm, and claims that the accounting information

caused the security price reaction. Another researcher finds evidence of security

price reaction to a different item of accounting information during a wide window beginning $12$ months prior to the release of the financial statements containing that item.

This researcher does not claim that the accounting information caused the security price

reaction, but only that the information and the market price reaction were associated.

Explain why a researcher can claim causation for a narrow window but not for a wide

window. Which price reaction constitutes the stronger evidence for usefulness of accounting

information? Explain.