中文摘要：

公众改善环境之意愿的最直接体现是支付意愿。在介绍了多项式概率模型及其层次贝叶斯估计方法后，利用问卷数据研究了北京市公众（大学生群体）对于改善长期空气质量的支付意愿。结果显示，为了在20年内北京市空气质量良级天数（API〈100）达到90％以上，公众的支付意愿为未来5年47元／人／月，支付意愿随时间的贴现率大约为3．8％。

英文摘要：

In this paper, the public＇s willingness to pay for the long-run air quality improvement is examined based on the internet survey data and the employed multinomial Probit model is estimated in a hierarchical Bayes framework. Our results show that the public＇s willingness to pay for the long- run increase in air quality to the best level in our survey in 20 years is about 47 RMB per person per month for the next 5 years, and the discount rate of that payment is about 3.8 %.