A Note on the Validity of the WSJ As a Source of "Event" Dates
检验《华尔街日报》作为事件日期来源的可靠性，发现许多公告实际在前一天已公开，提醒研究者注意日期偏差对事件研究结果的影响。
Many information content studies rely on the Wall Street Journal (WSJ) as the source of the date of the release of particular information to the market. delineation of the exact date of disclosure has gained importance as researchers have started using daily rates of return to evaluate the association of information with market excess returns. It is generally assumed that the WSJ is a reliable source, but there is some uncertainty about the degree of reliability of dates. A recent article by Penman highlighted this uncertainty: The mean abnormal return on day -1, where the largest effect is observed, is .92%. Many forecasts apparently become public on the day before they are reported in the Wall Street Journal.' This uncertainty motivated me to reopen an old data file. reliability of the dates of WSJ articles became a concern of mine in 1973 when I first became interested in this type of research. To satisfy myself about the accuracy of the WSJ as a source of event dates, I requested the public relations offices of 100 companies that were listed on the NYSE to place my name on the mailing list for all of their press releases. Sixty companies honored my request. A checklist was made for all earnings and dividends announcements for which the dates of press