log using matchid, text replace
set memory 500m
set more 1
program define matchid
#delimit cr
display "Merge previous year for `1'"
local lastyear=2002
use /homes/data/morg/annual/morg`2'
rename match match`2'
rename minsamp minsamp`2'
egen str2 filmage = concat(mage)
replace filmage = "99" if mage==.
if `1' == 1979 {
   gen matchp=0
}
else if (  `1' <= 2000 & `1' > 1979 ) {
   local prevyear=`2'-1
   if ( `1'==2000 ) { 
      local prevyear=99 
   }
   sort matchid filmage age sex race id
   display "Merging `1' file using morg`prevyear'.dta (year<=2000)"
   merge matchid using /homes/data/morg/annual/morg`prevyear'.dta
   gen matchp =(_merge==3 & minsamp`2'==8)
}
else if `1' >2000 {
   local prevyear=`1'-2001
   sort matchid filmage age sex race id
   display "Merging `1' file using morg0`prevyear'.dta (year>2000)"
   merge matchid using /homes/data/morg/annual/morg0`prevyear'.dta
   gen matchp =( _merge==3 & minsamp`2'==8)
}
if (`1' > 1979 ) {
   display "Dropping non-matches from the matchfile"
   drop if _merge==2
   display "Dropping the _merge variable"
   drop _merge
}
if `1' <1999 { 
   local nextyear = `2' + 1
   sort matchid age filmage sex race id
   display "Merging `1' file using morg`nextyear'.dta (year<2000)"
   merge matchid using /homes/data/morg/annual/morg`nextyear'.dta
   gen matchn =(_merge==3 & minsamp`2'==4)
}
else if ( `1' < `lastyear' & `1' >= 1999 ) {
   local nextyear = `2' + 1
   if ( `1' ==1999 ) { 
       local nextyear=0 
    }
   sort matchid age filmage sex race id
   display "Merging `1' file using morg0`nextyear'.dta (year>=1999 & year < `lastyear')"
   merge matchid using /homes/data/morg/annual/morg0`nextyear'.dta
   gen matchn=( _merge==3 & minsamp`2'==4)
}
else if ( `1' == `lastyear' ) {
   gen matchn=0
}
if ( `1' < `lastyear' ) {
   display "Dropping non-matches from the matchfile"
   drop if _merge==2
   display "Dropping the _merge variable"
   drop _merge
}
gen byte match2=matchp+matchn
display "Eliminating 'matches' that are too far apart in age"
replace match2=0 if nragedif==0
replace match`2'=0 if nragedif==0
display "Eliminating 'matches' with different sex"
list matchid sex  if match2==1 & sexdif==0
replace match2=0 if sexdif==0
replace match`2'=0 if sexdif==0
display "Eliminating 'matches' with different race"
replace match2=0 if racedif==0
replace match`2'=0 if racedif==0
*unab vlist:  _all
*sort `vlist'
sort mym intmonth state hhid hhnum id lineno
quietly by mym intmonth state hhid hhnum id lineno: gen dupm = cond(_N==1,0,_n)
*quietly by `vlist': gen dupm = cond(_N==1,0,_n)
replace match2=0 if dupm>0
replace match`2'=0 if dupm>0
sum match`2' match2
clear

end

*matchid 1979 79 79_83
*matchid 1980 80 79_83
*matchid 1981 81 79_83
*matchid 1982 82 79_83
*matchid 1983 83 79_83
*matchid 1984 84 84_88
*matchid 1985 85 84_88
*matchid 1986 86 84_88
*matchid 1987 87 84_88
*matchid 1988 88 84_88
*matchid 1989 89 89_93
*matchid 1990 90 89_93
*matchid 1991 91 89_93
*matchid 1992 92 89_93
*matchid 1993 93 89_93
*matchid 1994 94 94_97
*matchid 1995 95 94_97
*matchid 1996 96 94_97
*matchid 1997 97 94_97
matchid 1998 98 98
matchid 1999 99 98
matchid 2000 00 98
*matchid 2001 01 98
*matchid 2002 02 98