Backcasting the data

[Mario Amato Meno]

Dear Stata users,

I must confess that I am not familiar with this but, as from the title of the thread, I am looking for some advices to backcast the data.

In particular, I have yearly bilateral trade data at country level from 1990 - 2010 for single products.

I would like to backcast the data on export and import values up to 1980 for every single product/country-pair.

* Example generated by -dataex-. To install: ssc install dataex
clear
input int year str3(i_iso3 j_iso3) int sitc str15(export_val import_val)
1990 "AGO" "TGO" 6612 "1985000.00" "0.00"      
1990 "AGO" "CHN" 6645 "0.00"       "601.00"    
1990 "AGO" "CHN" 6785 "0.00"       "1762.00"   
1990 "AGO" "CHN" 6991 "0.00"       "15282.00"  
1990 "AGO" "CHN" 7243 "0.00"       "9839.00"   
1990 "AGO" "CHN" 7281 "0.00"       "9165.00"   
1990 "AGO" "CHN" 7283 "0.00"       "4364.00"   
1990 "AGO" "CHN" 7362 "0.00"       "1478.00"   
1990 "AGO" "CHN" 7373 "0.00"       "553.00"    
1990 "AGO" "CHN" 7422 "0.00"       "599.00"    
1990 "AGO" "CHN" 7442 "0.00"       "5448.00"   
1990 "AGO" "CHN" 7452 "0.00"       "4324.00"   
1990 "AGO" "CHN" 7721 "0.00"       "616.00"    
1990 "AGO" "CHN" 7821 "0.00"       "20800.00"  
1990 "AGO" "CHN" 7868 "0.00"       "821.00"    
1990 "AGO" "CHN" 6648 "0.00"       "2879.00"   
1990 "AGO" "CHN" 7415 "0.00"       "763.00"    
1990 "AGO" "CHN" 7611 "0.00"       "566.00"    
1990 "AGO" "CHN" 7622 "0.00"       "60740.00"  
1990 "AGO" "CHN" 7628 "0.00"       "54921.00"  
1990 "AGO" "CHN" 7754 "0.00"       "11272.00"  
1990 "AGO" "CHN" 7757 "0.00"       "13325.00"  
1990 "AGO" "CHN" 7781 "0.00"       "10751.00"  
1990 "AGO" "CHN" 8124 "1368.00"    "21236.00"  
1990 "AGO" "CHN" 8852 "0.00"       "14676.00"  
1990 "AGO" "CHN" 8942 "0.00"       "5426.00"   
1990 "AGO" "CHN" 8947 "0.00"       "941.00"    
1990 "AGO" "CHN" 6644 "0.00"       "1679.00"   
1990 "AGO" "CHN" 6931 "0.00"       "666.00"    
1990 "AGO" "CHN" 6973 "0.00"       "2823.00"   
1990 "AGO" "CHN" 7731 "0.00"       "1670.00"   
1990 "AGO" "CHN" 8219 "0.00"       "45576.00"  
1990 "AGO" "CHN" 6953 "0.00"       "2202.00"   
1990 "AGO" "CHN" 6960 "0.00"       "49396.00"  
1990 "AGO" "CHN" 6974 "0.00"       "1312835.00"
1990 "AGO" "CHN" 7852 "0.00"       "37087.00"  
1990 "AGO" "CHN" 8851 "0.00"       "126705.00" 
1990 "AGO" "CHN" 8994 "0.00"       "6351.00"   
1990 "AGO" "CHN" 8998 "0.00"       "6439.00"   
1990 "AGO" "CHN" 5334 "0.00"       "15947.00"  
1990 "AGO" "CHN" 5417 "0.00"       "6366.00"   
1990 "AGO" "CHN" 8939 "0.00"       "10188.00"  
1990 "AGO" "CHN" 5331 "0.00"       "527.00"    
1990 "AGO" "CHN" 8742 "0.00"       "699.00"    
1990 "AGO" "CHN" 8991 "0.00"       "13991.00"  
1990 "AGO" "CHN" 6513 "0.00"       "2289.00"   
1990 "AGO" "CHN" 6522 "551765.00"  "0.00"      
1990 "AGO" "CHN" 6536 "0.00"       "10500.00"  
1990 "AGO" "CHN" 6583 "0.00"       "228837.00" 
1990 "AGO" "CHN" 6575 "0.00"       "31951.00"  
1990 "AGO" "CHN" 6584 "0.00"       "1908330.00"
1990 "AGO" "CHN" 8310 "0.00"       "45591.00"  
1990 "AGO" "CHN" 8429 "0.00"       "49199.00"  
1990 "AGO" "CHN" 8434 "0.00"       "8782.00"   
1990 "AGO" "CHN" 8441 "0.00"       "12326.00"  
1990 "AGO" "CHN" 8451 "0.00"       "347614.00" 
1990 "AGO" "CHN" 8452 "0.00"       "4340.00"   
1990 "AGO" "CHN" 8459 "0.00"       "1419.00"   
1990 "AGO" "CHN" 8462 "0.00"       "13592.00"  
1990 "AGO" "CHN" 8463 "0.00"       "126240.00" 
1990 "AGO" "CHN" 8471 "0.00"       "65779.00"  
1990 "AGO" "CHN" 8472 "0.00"       "67931.00"  
1990 "AGO" "CHN" 8484 "0.00"       "1979.00"   
1990 "AGO" "CHN" 8510 "0.00"       "520493.00" 
1990 "AGO" "CHN"  542 "0.00"       "1649568.00"
1990 "AGO" "CHN" 6512 "217705.00"  "0.00"      
1990 "AGO" "CHN" 6595 "0.00"       "33925.00"  
1990 "AGO" "CHN" 6951 "0.00"       "9881.00"   
1990 "AGO" "CHN" 7853 "0.00"       "8895.00"   
1990 "AGO" "CHN" 8830 "0.00"       "1248.00"   
1990 "AGO" "CHN" 8993 "0.00"       "15843.00"  
1990 "AGO" "CHN" 9310 "0.00"       "2282.00"   
1990 "AGO" "CYP" 7649 "4778.00"    "0.00"      
1990 "AGO" "HKG" 6991 "0.00"       "34151.00"  
1990 "AGO" "HKG" 7162 "0.00"       "191653.00" 
1990 "AGO" "HKG" 7243 "0.00"       "53352.00"  
1990 "AGO" "HKG" 7245 "0.00"       "1362.00"   
1990 "AGO" "HKG" 7247 "0.00"       "1643.00"   
1990 "AGO" "HKG" 7434 "0.00"       "19350.00"  
1990 "AGO" "HKG" 7452 "0.00"       "16472.00"  
1990 "AGO" "HKG" 7721 "0.00"       "2670.00"   
1990 "AGO" "HKG" 7758 "0.00"       "8450.00"   
1990 "AGO" "HKG" 7784 "0.00"       "900.00"    
1990 "AGO" "HKG" 7821 "0.00"       "78605.00"  
1990 "AGO" "HKG" 7831 "0.00"       "12554.00"  
1990 "AGO" "HKG" 7849 "0.00"       "23198.00"  
1990 "AGO" "HKG" 7851 "0.00"       "198185.00" 
1990 "AGO" "HKG" 6648 "0.00"       "598.00"    
1990 "AGO" "HKG" 7415 "0.00"       "36410.00"  
1990 "AGO" "HKG" 7511 "0.00"       "4798.00"   
1990 "AGO" "HKG" 7512 "0.00"       "48582.00"  
1990 "AGO" "HKG" 7518 "0.00"       "5718.00"   
1990 "AGO" "HKG" 7522 "4123.00"    "5904.00"   
1990 "AGO" "HKG" 7523 "4560.00"    "630887.00" 
1990 "AGO" "HKG" 7525 "0.00"       "224507.00" 
1990 "AGO" "HKG" 7599 "5434.00"    "76315.00"  
1990 "AGO" "HKG" 7611 "0.00"       "183974.00" 
1990 "AGO" "HKG" 7612 "1137.00"    "22336.00"  
1990 "AGO" "HKG" 7621 "0.00"       "5647.00"   
1990 "AGO" "HKG" 7622 "0.00"       "84355.00"  
end

My questions are:

1) is there any command or ado in Stata to do this? Maybe looking at the trends(?)

2) once this is done, is there a way to validate the data with already existing data (that I already have)?

It would be great also if you could provide some references!!

Thank you

Mario