代码如下:
法一:
tsset sk year
gen yinglimean3=(l.meayingli+l2.meayingli+l3.meayingli)/3
gen yingli1sd3= (((l.meayingli-yinglimean3)^2+(l2.meayingli-yinglimean3)^2+(l3.meayingli-yinglimean3)^2)/3)^.5
法2:
bys sk (year):gen meayingli1=meayingli[_n-1]
bys sk (year):gen meayingli2=meayingli[_n+1]
egen yingli2sd3=rowsd( meayingli meayingli1 meayingli2)
drop meayingli1 meayingli2
法三:
bys sk (year): g m=(meayingli+meayingli[_n-1]+meayingli[_n-2])/3
bys sk (year): g yingli3sd3=sqrt(((meayingli[_n-2]-m)^2+(meayingli[_n-1]-m)^2+(meayingli-m)^2)/2)
drop m
法4:
xtset sk year
tssmooth ma s=meayingli,w(2,1)
tssmooth ma s2=meayingli^2,w(2,1)
bys sk (year): g yingli4sd3=sqrt((s2-s^2)*3/2) if _n>2
drop s s2
法5:
sort sk year
xtset sk year
tsfill
mvsumm ayingli,stat(sd) win(3) gen(nyingli) end force
gen yingli5sd3 = nyingli/myingli