Maria Garcia US Census Bureau UNECE/SDE, Oslo, Norway, September 2012 An Application of Selective Editing to the US Census Bureau Trade Data

Foreign Trade Statistics Programs Official source of US international merchandise trade statistics Electronic data collection Complete enumeration Pre – editing: check for fatal errors Micro editing –Range and ratio edits –Automatic imputation –“Rejects” – imputation not successful

Foreign Trade Data Processing Rejects –Distribute among analysts for manual correction. –Analysts review large number of records under tight time constraints Goal: Use selective editing to identify highly suspicious errors having a high potential effect on the estimates –Value (V) –Quantity (Q) –Shipping weight (SW)

Hidiroglou-Berthelot Method (HB)

HB Method for Our Trade Data

HB for Our Trade Data (Cont’d)

Effect on Publication Totals

Simulation and Evaluation

Evaluation Results Examining results at lowest level of aggregation: –Data users may closely scrutinize the statistics for particular types of products –Ex: import/export of rough diamonds –Kimberley Process - joint governments, industry and civil society initiative to stem the flow of conflict diamonds

Evaluation Results

Customer’s Feedback Subject matter experts questioned: –High ranking given to records that by experience they consider insignificant to final cell estimates –Low ranking given to records that would have been flagged for manual correction

Total Value (V) Total Quantity (Q) Unit Price (V/Q) Ratio Bounds Reported cell total $102,1907,217$ Reported suspicious Record $3,024 7,144$ Final suspicious record $3,02410$ Final cell total $102,19083$1, Commodity XXXXXXXXXX Customer’s Feedback

Total Value (V) Total Quantity (Q) Unit Price (V/Q) Ratio Bounds Lower Bound Upper Bound 128 records, 87 records imputed, three rejects $3,142,622129,973,502$ Final cell total All three rejects corrected $3,142,6221,230,629$ Selective editing cell total Two highest ranked records corrected $3,142,6221,804,699$ Commodity YYYYYYYYYY Customer’s Feedback

Concluding Remarks

Thank you!