Analysts’Optimism and Selection Bias

• Autor(a) principal: Martinez, Antônio Lopo
• Data de Publicação: 2007
• Tipo de documento: Artigo
• Idioma: eng; por
• Título da fonte: BBR. Brazilian Business Review (English edition. Online)
• Texto Completo: http://www.bbronline.com.br/index.php/bbr/article/view/415
• topic: optimism; earnings forecasts; selection bias; analysts; otimismo; previsões de resultados; viés de seleção; analistas

This paper is an empirical examination, drawing on the Institutional Brokers Estimate System (I/B/E/S) database, of analysts’ earnings forecast optimism for Brazilian companies. The study found that analysts were optimistic on average and performed poorly in terms of precision and accuracy. The study period was January 1995 to December 2002. The forecasting errors in one period were correlated with the errors of the following period. There was evidence of persistent consensus errors among analysts, with those who were persistently optimistic outweighing those who were persistently pessimistic. A possible explanation for this predominant overoptimism is selection bias. In order to adjust analysts’ consensus forecasts, an optimization methodology is suggested, providing results that minimize the optimism bias. The evidence presented is relevant, especially for those using analysts’ earnings forecasts as an input in their stock valuation models.