中文摘要：

本文以2008-2014年中国证券市场的分析师评级调整为样本,基于学习模型进行理论分析,研究经济形势对评级调整的参考价值的影响,结合调整方向、分析师特征等,挖掘该影响机制。研究发现：中国市场上,分析师上调评级在经济形势不好时比在经济形势好时更有参考价值,但是下调评级的参考价值在不同经济形势下差异不显著;来自明星分析师、明星券商的上调评级更有参考价值,且短期内,券商名气对累计超额收益的作用比分析师名气的作用更大。

英文摘要：

Based on a learning model, this paper examines a sample of analysts＇ rating revisions for Chinese stock market listed firms during 2008-2014 to explore the influence of the economic situation on the value of analysts＇ rating revisions. We mine the impact mechanisms between them considering rating feature and analyst characteristics, etc. Our results indicate that, in Chinese stock market, upgrades are more valuable in bad times. However, there is no significant difference for downgrades between good times and bad times. Furthermore, upgrades from star analysts and star brokers are more valuable in bad times,and star brokers contribute more to the cumulative abnormal return than star analysts.