Derivation
variable: prefrest1 [decade estimate of previous village start] table[s]: tb_tbx, tb_tbxto2007, tbold_part1/2, tb_tbo, tb_tboto2007, tbold_control)
variable: prefrmm1 [month of previous village start] (table[s]: tb_tbx, tb_tbxto2007, tbold_part1/2, tb_tbo, tb_tboto2007, tbold_control)
variable: prefryear1 [year of previous village start] (table[s]: tb_tbx, tb_tbxto2007, tbold_part1/2, tb_tbo, tb_tboto2007, tbold_control)
recode prefrmm1 0=1
replace prefryear1=1895 if prefrest1==1
replace prefryear1=1905 if prefrest1==2
replace prefryear1=1915 if prefrest1==3
replace prefryear1=1925 if prefrest1==4
replace prefryear1=1935 if prefrest1==5
replace prefryear1=1945 if prefrest1==6
replace prefryear1=1955 if prefrest1==7
replace prefryear1=1965 if prefrest1==8
replace prefryear1=1975 if prefrest1==9
replace prefryear1=1985 if prefrest1==10
replace prefryear1=1995 if prefrest1==11
replace prefryear1=1895 if prefrest1==12
replace prefryear1=1907 if prefrest1==13
replace prefryear1=1924 if prefrest1==14
replace prefryear1=1940 if prefrest1==15
replace prefryear1=1951 if prefrest1==16
replace prefryear1=1960 if prefrest1==17
replace prefryear1=1970 if prefrest1==18
recode prefryear1 9999=. 0=.
gen prefrdate1=mdy(prefrmm1,15,prefryear1) if prefrmm1~=. & prefryear1~=.
replace prefrdate1=mdy(6,15,prefryear1) if prefrmm1==. & prefryear1~=.
