讲座题目：Misspecified Learning in Technology Adoption: Experimental Evidence from Fertilizer Use in China
主讲人：林炜（香港中文大学深圳分校）
讲座时间：2025年5月14日 周三 上午10:30-12:00
讲座地点：北京大学国家发展研究院承泽园校区245教室
组织者：
(国家发展研究院) 李力行、席天扬、徐化愚、于航、王轩、易君健、黄清扬
(经济学院) 刘冲、吴群峰、曹光宇、年永威
(光华管理学院）张晓波、仇心诚

摘要：This paper investigates agents' learning about multiple interacting technologies in the context of fertilizer application in China. We first present experimental evidence that farmers overuse nitrogen fertilizers and underuse phosphorus and potassium fertilizers. Our first-phase intervention provides customized fertilizer recommendations and leads to reduced use of nitrogen and increased use of phosphorus and potassium. Average yields and revenues are 5%-7% higher, while total fertilizer costs remain unchanged. Survey data suggest that farmers overestimate the return to nitrogen because it produces a salient signal of increasing greenness in crops, but they underestimate the effectiveness of phosphorus and potassium because their effects are barely observable during the growing stages. We propose a model of misspecified learning in which agents face two technologies with unknown returns. When learning about the effectiveness of these technologies, an overestimation of the return to the first causes undervaluation and underuse of the second. We further test the model, with a second-phase intervention that distributes leaf color charts to farmers to correct their overestimation of the return to greenness. Consistent with the model's prediction, the intervention not only immediately reduces farmers' nitrogen use, but also induces gradual learning about phosphorus and potassium. Both the share of farmers using phosphorus and that of potassium increase by 6 percentage points, relative to 3% and 9% in the control group.

个人简介：林炜，香港中文大学（深圳）经管学院助理教授，2022年获得加州大学伯克利分校博士学位。主要研究领域包括发展经济学、实证贸易、中国经济等。主持自然科学基金青年项目，广东自科面上项目等，研究成果发表在《管理世界》、Journal of Economic Behavior & Organization，并有研究收到了Quarterly Journal of Economics的修订邀请。