国外的有效性研究盈利预测和投资评级的准确性通常是衡量一个分析师优劣的重要依据。美国由于证券市场比较成熟,具有多年的盈利预测数据,特别是I/B/E/S和FirstCall的数据库都收集了近几十年的卖方分析师预测。美国早期的研究主要 Validity of Foreign Studies The accuracy of earnings forecasts and investment ratings is often an important measure of the pros and cons of an analyst. The United States has many years of earnings forecasts as the securities market is relatively mature. In particular, the database of I / B / E / S and FirstCall collects sellers’ forecasts in recent decades. The main research in the United States earlier