A Synthetic Instrumental Variable Method: Using the Dual Tendency Condition for Coplanar Instruments
合成工具变量方法:利用共面工具变量的双重趋势条件
Traditional instrumental variable (IV) methods often struggle with weak or invalid instruments and rely heavily on external data. We introduce a Synthetic Instrumental Variable (SIV) approach that constructs valid instruments using only existing data. Our method leverages a data-driven dual tendency (DT) condition to identify valid instruments without requiring external variables. SIV is robust to heteroscedasticity and can determine the true sign of the correlation between…