echo0719 发表于 2016-12-15 18:57 
非常感谢!如果您想到做法,烦请告知小的
我去问了别人(我自己也学习了新方法),Oded Mcdossi 提出一个非常好的方法(
你怎能不爱 Stata!!!):
- clear
- input str4 firm float year str8 ind float x
- "A" 2000 "I1" 1
- "A" 2001 "I1" 2
- "A" 2002 "I1" 3
- "B" 2000 "I1" 1.1
- "B" 2001 "I1" 2.1
- "B" 2002 "I1" 3.1
- "C" 2000 "I1" 1.2
- "C" 2001 "I1" 2.2
- "C" 2002 "I1" 3.2
- "D" 2000 "I2" 11
- "D" 2001 "I2" 22
- "D" 2002 "I2" 33
- "E" 2000 "I2" 11.1
- "E" 2001 "I2" 21.1
- "E" 2002 "I2" 31.1
- "F" 2000 "I2" 12.2
- "F" 2001 "I2" 22.2
- "F" 2002 "I2" 32.2
- "G" 2000 "I2" 112.2
- "G" 2001 "I2" 222.2
- "G" 2002 "I2" 232.2
- end
- preserve
- rename (firm x)(firm_2 x_2)
- tempfile join
- save `join'
- restore
- joinby ind year using `join'
- keep if firm<firm_2
- sort ind year firm firm_2
复制代码