更多的教育财政投入能否带来更好的教育产出一直是教育经济学领域重点研究的问题，由于教育产出水平影响因素复杂，相关讨论未得到一致的结论。本文借鉴工具变量法的思想，引入西部地区两基政策作为第三方变量，通过政策效果评估研究了教育财政投入对教育产出的影响。

首先，我们通过对西部地区两基政策进行梳理，解读政策目标和主要措施，来了解该政策和教育财政投入及教育产出之间的关系，并分析了政策颁布前后西部地区教育财政投入和教育产出的整体情况。其次，我们通过使用合成控制法进行政策效果评估，定量分析了政策的实施对西部各省份教育财政投入和教育产出的影响。最后，基于以上研究基础，我们借鉴工具变量法的思想，将西部地区两基政策作为第三方变量，讨论了教育财政投入和教育产出的因果关系。

      研究发现，第一、西部地区两基政策的主要措施是从人、财、物各方面加大对西部地区教育财政投入；西部地区教育财政投入和产出水平都呈现出逐年增加的趋势，其中教育财政投入的增加速度在两基政策实施后有了明显的提高，教育产出水平未体现类似的变化。第二、量化分析发现，在所有西部省份中，两基政策仅对陕西省的教育财政投入和产出水平有显著的正向影响，陕西省的教育财政投入水平和教育产出水平均有了提高。

     综合以上研究结论，我们认为如果把西部地区两基政策看成工具变量，两基政策给陕西省教育产出水平带来的正向影响是来自于陕西省教育财政投入的增加。因此，我们可以认为陕西省在西部地区两基政策实施后，教育财政投入的增加带来了更好的教育产出，在一定程度上说明教育财政投入的有效性。本文创造性的将工具变量思想与政策效果评估相结合的分析框架，在一定程度上能给相关研究提供一些有益借鉴。

      Whether more financial investment in education can bring better educational output has been a key issue in the field of educational economics. Because of the complicated factors affecting the level of educational output, the relevant discussions have not reached a unanimous conclusion. Based on the theory of instrumental variable method, this paper studies the effect of educational financial input on educational output by introducing the two-base policy in western China as the third-party variable.

     First of all, we understand the relationship between the policy and educational financial input and educational output by sorting out the two-base policy in the Western Region and interpreting the policy objectives and major measures, it also analyzes the whole situation of educational financial input and educational output before and after the promulgation of the policy. Secondly, we use the synthetic control method to evaluate the effect of the policy, and analyze the impact of the implementation of the policy on the financial input and output of education in the western provinces. Finally, we use the idea of instrumental variable method to discuss the causality between educational financial input and educational output.

      The study found that the main measures of the first two basic policies in the western region are to increase the financial input to education in the western region from the aspects of people, finance and goods, and that the financial input and output level of education in the western region have shown an increasing trend year by year, among them, the increase speed of educational financial input has improved obviously after the implementation of the two basic policies, and the educational output level has not reflected similar changes. Second, the quantitative analysis found that in all the western provinces, the two-base policy only had a significant positive impact on the level of educational financial input and output in Shaanxi province, the level of education financial input and the level of education output in Shaanxi province have improved.

      Based on the above conclusions, we think that if the two-base policy is regarded as a tool variable, the positive impact of the two-base policy on the level of educational output in Shaanxi province comes from the increase of educational financial input in Shaanxi Province. Therefore, we can think that after the implementation of the two-base policy in the western region of Shaanxi province, the increase of educational financial input has brought about better educational output, which shows the effectiveness of educational financial input to a certain extent. This paper creatively combines the theory of instrumental variables with the analysis framework of policy effect evaluation, which can provide some useful references for related research.