不景氣期間的不確定性很高，而高度的不確定性會使得分析師的預測任務更加困難，因此分析師的預測在景氣不佳的時候是否更有價值是不確定的，本研究以券商的盈餘預測資料為樣本基礎，臺灣上市櫃公司為研究對象，且樣本期間2000至2018年的年盈餘預測資料來探討分析師的盈餘預測誤差和景氣兩者之間的關係，利用(1)每股盈餘；(2)股票波動性；(3)每股淨值三種絕對預測誤差衡量方法來捕捉分析師的預測誤差趨勢，並進一步探究分析師的盈餘預測在不景氣期間是否存在相當程度的準確性與價值，希望藉此投資人能夠慎選自己的投資參考標的，在決定投資策略前掌握更好、更準確的預測資訊。
本研究實證結果發現分析師在不景氣期間，三種衡量方式所得出來的誤差有所差異，每股盈餘和每股淨值的衡量方式結果相似，分析師的預測誤差與金融危機和高度不確定性呈顯著正相關，代表分析師的預測準確性普遍在不景氣時較低，只是按照股票波動性為衡量方式的預測誤差反而在不景氣期間是更準確的，可能的原因是股價的變動會對分析師的盈餘預測產生較大的影響力，此衡量方式更能解釋每單位不確性增加，分析師的預測誤差確實跟著降低。
本研究結果另外發現三種不同的景氣分類也存在相異的結果，儘管使用不同衡量方式，結果都顯示分析師的預測誤差與經濟蕭條期間呈顯著負相關，與金融危機和高度不確定性期間卻呈顯著正相關，代表經濟景氣越不好，分析師的預測誤差反而越小，可能的原因是股票市場的反應程度比經濟景氣來得快速，分析師已於股票市場獲得相關資訊，因此對盈餘預測會更謹慎。

Uncertainty in bad times is high, and high uncertainty will make the analyst’s forecasting more difficult. It is unclear whether the analyst's forecast is more valuable in bad times or not. The research sample is based on broker’s earnings forecast data, the listed companies in Taiwan are the research objects, and all the sample period are from 2000 to 2018. The research aims to explore the relationship between the analyst's earnings forecast error and the bad times. Using three absolute forecast error measures: (1) earnings per share, (2) annualized stock volatility, and (3) book value per share to capture the analyst's forecast error trend, and further explore whether the analyst's earnings forecast has a considerable degree of accuracy during the bad times. With the findings, this research hopes to give investors a chance to carefully select their investment references and targets. What’s more, investors can obtain better and more accurate forecast information before they make investment strategies.
The empirical results of this study show that during the bad times, the forecast error scaled by three measures are quite different. Regression results of the forecast error scaled by earnings per share and book value per share are similar. The analyst's forecast error is significantly positive correlated with Crisis and Uncertainty, which means analysts’ forecast accuracy is generally lower in the bad times. However, analysts’ forecast error scaled by annualized stock volatility is much lower in bad times, which is more accurate. The possible reason is that the stock-price impact on analysts’ forecast is greater in bad times. This measurement is more able to explain the analyst's forecast error will decrease with the increase of uncertainty per unit.
The results of this study additionally found that there are different results for the three classifications of the bad times. Although different measures are used, the results present that the analyst's forecast error is significantly negative correlated with Recession, but positive correlated with Crisis and Uncertainty. It means that the worse the economy is, the smaller the forecast error is. The possible reason is that the stock market responses more quickly than the economy. Analysts can get relevant information in the stock market first, so their forecast for EPS will be more cautious.

(一) 中文部分
賴紀誠、林問一、劉亞秋（民100）。台灣股市券商分析師盈餘預測之利益衝突。臺大管理論叢，22(1)，357-390。
王明昌、周邦營 （民103）。公司治理與分析師盈餘預測誤差。建國科大社會人文期刊，33(2)，19-38。
蘇玄啟、羅仙法、袁正達、楊俊彬（民105）。股票市場流動性與總體景氣循環：來自台灣的廣泛性證據。管理與系統，23(1)，65-106。
一分鐘搞懂台股30年（民102年10月）。CMoney官方。取自https://www.cmoney.tw/notes/note-detail.aspx?nid=6496
細數金融史近20年來的9隻黑天鵝（民106年02月）。華爾街見聞。取自https://www.stockfeel.com.tw/%E7%B4%B0%E6%95%B8%E9%87%91%E8%9E%8D%E5%8F%B2%E8%BF%9120%E5%B9%B4%E4%BE%86%E7%9A%849%E9%9A%BB%E9%BB%91%E5%A4%A9%E9%B5%9D/
楊卓翰（民107年3月）。誰說分析師已死？天王級外資老將，如何找到人生新舞台。天下雜誌網。取自https://www.cw.com.tw/article/article.action?id=5088983&fbclid=IwAR1MbOM9nqIPTSQ8D-XJko7CtFtw8nBSj5ntybEYXDhfnDhfHCUNXDCCF2k

(二) 英文部分
Bloom, N. (2009). The Impact of Uncertainty Shocks. Econometirca, 77(3), 623-685. doi:http://dx.doi.org/10.3386/w13385
Chan, W. S. (2003). Stock price reaction to news and no-news: drift and reversal after headlines. Journal of Financial Economics, 70(2), 223-260.
Chopra, V. K. (1998). Why so much error in analysts' earnings forecasts? Financial Analysts Journal, 54(6), 35-42.
Clement, M. B. (1999). Analyst forecast accuracy: Do ability, resources, and portfolio complexity matter? Journal of Accounting & Economics, 27(3), 285-303.
Clement, M. B., & Tse, S. Y. (2005). Financial Analyst Characteristics and Herding Behavior in Forecasting. The Journal of Finance, 60(1), 307-341.
Cote, J., & Goodstein, J. (1999). A breed apart? Security analysts and herding behavior. Journal of Business Ethics, 18(3), 305-314.
Espahbodi, H., Espahbodi, P., & Espahbodi, R. (2015). Did Analyst Forecast Accuracy and Dispersion Improve after 2002 Following the Increase in Regulation? Financial Analysts Journal, 71(5), 20-37.
Glode, V. (2011). Why mutual funds “underperform”. Journal of Financial Economics, 99(3), 546-559. doi:https://doi.org/10.1016/j.jfineco.2010.10.008
Green, C., Jegadeesh, N., & Tang, Y. (2009). Gender and job performance: Evidence from Wall Street. Financial Analysts Journal, 65(6), 65‐78.
Groysberg, B., Healy, P., Nohria, N., & Serafeim, G. (2011). What Factors Drive Analyst Forecasts? Financial Analysts Journal, 67(4), 18-29.
Hirshleifer, D., Levi, Y., Lourie, B., & Teoh, S. H. (2019). Decision fatigue and heuristic analyst forecasts. Journal of Financial Economics. doi:https://doi.org/10.1016/j.jfineco.2019.01.005
Hope, O.-K., & Kang, T. (2005). The association between macroeconomic uncertainty and analysts' forecast accuracy. Journal of International Accounting Research, 4(1), 23-38.
Kerl, A., Schürg, C., & Walter, A. (2014). The impact of Financial Times Deutschland news on stock prices: post-announcement drifts and inattention of investors. Financial Markets and Portfolio Management, 28(4), 409-436. doi:http://dx.doi.org/10.1007/s11408-014-0238-9
Li, X., Sullivan, R. N. C. F. A., Xu, D., & Gao, G. C. F. A. (2013). Sell-Side Analysts and Gender: A Comparison of Performance, Behavior, and Career Outcomes. Financial Analysts Journal, 69(2), 83-94.
Lim, T. (2001). Rationality and Analysts’ Forecast Bias. The Journal of Finance, 56(1), 369-385.
Lin, L., & Kuo, C.-J. (2007). Stock recommendations and analyst conflicts of interest: evidence from the Taiwan stock market. Web Journal of Chinese Management Review, 10(2), 1-24.
Loh, R. K., & Stulz, R. M. (2018). Is Sell‐Side Research More Valuable in Bad Times? The Journal of Finance, 73(3), 959-1013. doi:http://dx.doi.org/10.1111/jofi.12611
Merkley, K., Michaely, R., & Pacelli, J. (2017). Does the Scope of the Sell-Side Analyst Industry Matter? An Examination of Bias, Accuracy, and Information Content of Analyst Reports. The Journal of Finance, 72(3), 1285-1334. doi:http://dx.doi.org/10.1111/jofi.12485
Michaely, R., & Womack, K. L. (1999). Conflict of interest and the credibility of underwriter analyst recommendations. The Review of Financial Studies, 12(4), 653-686.
Mikhail, M. B., Walther, B. R., Willis, R. H., & Jacob, J. (1997). Do security analysts improve their performance with experience? / Discussion. Journal of Accounting Research, 35, 131-166.
Newsome, J. P. (2005). Ethical Issues Facing Stock Analysts. Geneva Papers on Risk & Insurance, 30(3), 451-466. doi:http://dx.doi.org/10.1057/palgrave.gpp.2510033
Phillips, D. J., & Zuckerman, E. W. (2001). Middle-status conformity: Theoretical restatement and empirical demonstration in two markets. The American Journal of Sociology, 107(2), 379-429. doi:http://dx.doi.org/10.1086/324072
Pinho, C., Madaleno, M., & Santos, H. (2013). The Usefulness of Financial Analysts' Reports: A Content Analysis. International Journal of Management, 30(2), 631-648.
Robert, G. E., & Svetlana, K. (2019, May). The Investor Revolution. Harvard Business Review. Retrieved from https://hbr.org/2019/05/the-investor-revolution
Schmalz, M. C., & Zhuk, S. (2018). Revealing downturns. The Review of Financial Studies, 32(1), 338‐373.
Spyrou, S. (2013). Herding in financial markets: a review of the literature. Review of Behavioral Finance, 5(2), 175-194. doi:http://dx.doi.org/10.1108/RBF-02-2013-0009
Thomas, H. D. (2016). Wall Street Jobs Won’t Be Spared from Automation. Harvard Business Review. Retrieved from https://hbr.org/2016/12/wall-street-jobs-wont-be-spared-from-automation
Trueman, B. (1994). Analyst Forecasts and Herding Behavior. The Review of Financial Studies (1986-1998), 7(1), 97.
Wu, Y., Liu, T., Han, L., & Yin, L. (2018). Optimistic bias of analysts' earnings forecasts: Does investor sentiment matter in China? Pacific-Basin Finance Journal, 49, 147-163. doi:https://doi.org/10.1016/j.pacfin.2018.04.010