rename a003000000 book_equity // 所有者权益合计
rename a003102000 retain_earn // 资本公积(留存收益)
drop if (book_equity<=0|retain_earn<=0) //讨论合理性?
qui tsset
gen e = D.book_equity + D.retain_earn
gen d = D.TD // 负债总额
gen sum_ed = e+d // 各年度之和
bysort id: gen SUM_ed = sum(e+d) // 分母: Baker(2002, Eq.3, pp.12)
gen weight = sum_ed/SUM_ed // 权重: Eq.3, 求和符号内部部分
replace weight=0 if weight<0 // 权重不能小于零, Baker(2002,pp.12)
gen weight_MB = weight*MB
bysort id: gen MB_EFWA = sum(weight_MB)
gen MB_EFWA0 = MB_EFWA // 备份一份,留待后用
*-处理离群值(非常重要)
sum MB_EFWA, detail // 存在严重的离群值
panels id if (MB_EFWA>10) // 统计存在此问题的公司数目
replace MB_EFWA=. if MB_EFWA>10 // Baker(2002,p.12, Footnote 8)
sum MB_EFWA, detail // 此时还有离群值吗?
graph box MB_EFWA // 箱型图