连老师:
您好!
Stata 学术论文专题
Chang&Wong,2009,JCF -
* Chang, E. C., Wong, S. M. L., 2009.
* Governance with multiple objectives:
* Evidence from top executive turnover in china.
* Journal of Corporate Finance, 15(2): 230-244.
do文档
第457-464行
*-Tenure
dropvars tenure*
bysort id ct3: egen tenure = min(dyears)
bysort id: egen tenure_av = mean(tenure)
replace tenure = tenure_av if tenure==. // 缺漏值采用公司均值代替
bysort industry year: egen tenure_av_sic = mean(tenure)
replace tenure = tenure_av_sic if tenure==.
br id year dyears chgdt CT_yes CT_yes_miss ct123 ct3 tenure //查验处理过程
问题:
第462-463行:
bysort industry year: egen tenure_av_sic = mean(tenure)
replace tenure = tenure_av_sic if tenure==.
缺漏值已经由公司均值代替(第460-461行),这里缺漏值又由行业调整的均值替代,这两个替代是否有重复,后者(行业调整)是否会覆盖掉前者(公司均值),因为命令都是replace tenure =?
bysort id: egen tenure_av = mean(tenure) 已经以公司为单位算出均值,
bysort industry year: egen tenure_av_sic = mean(tenure) 为什么又以行业和年度为单位算出均值呢?
这二者有什么联系?对于替代缺漏值是否会重复?
谢谢连老师!