Stata学习：如何构建企业跨地区投资变量？

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文献来源 trans-regional investment To determine the number of subsidiaries the parent firm has invested in cities outside of its headquarters, we take the logarithm of the total number of subsidiaries and plus 1 to measure firms’ trans-regional investment (invest). Qu, X., Xia, J. (2024). Environmental regulation and firms' trans-regional investment: Evidence from the implementation of the New Environmental Protection Law. Finance Research Letters. 数据来源 清洗数据 cd C : \ Download u STK_NotesSubJoint_2023 , clear keep if ISExit == 0 regexm ( RelationshipCode , "2" ) keep if regexm ( End , "-12-31" ) keep Stkcd year RegisterAddress drop if mi ( R ) g n = 0 collapse ( count ) n , by ( S y R ) sa _1 , replace * u STK_LISTEDCOINFOANL_2023 + , clear keep Stkcd year CITY g i = substr ( C , 1 , 6 ) sa _2 , replace * u _1 , clear joinby S y using _2 g ………………………………