Designing the 2007 Commodity Flow Survey Authors: Scot Dahl, William C. Davie, Jr US Census Bureau Presented by: Ruth Detlefsen US Census Bureau June 19, 2007

2 Survey Description Conducted once every five years Partnership with BTS Includes establishments in mining, manufacturing, wholesale, and some retail and services industries Also selected auxiliary establishments

3 Summary of Changes for 2007 Scope & Coverage Frame Data Questionnaire design Sample design

4 Scope & Coverage Considerations Added retail fuel oil dealers –NAICS Added publishers –NAICS 5111 & Conduct an advance survey of auxiliaries

5 Frame Improvement Improved quality of data associated with auxiliaries Frame counts

6 Auxiliaries Support establishments of multi-unit companies CFS includes auxiliaries in: –Warehousing & storage (NAICS 4931) –Corporate, Subsidiary, & Regional Managing Offices (NAICS ) Many are not shippers Initial estimate of shipping activity is deficient for those that ship

7 Advance Survey In 2006, conducted an advance survey: One page questionnaire, 2 versions –Auxiliaries (NAICS 4931 & ) –Other large inscope establishments Purpose: –Identify non-shipping auxiliaries –Improve measure of shipping activity for auxiliaries (annual value of shipments) –Identify a contact person for all

8 Advance Survey Response rates: Auxiliaries: 87% Large establishments: 75%

9 Advance Survey Measures of shipment activity

10 Questionnaire Development Three rounds of cognitive visits Questionnaire changes –Improved layout and question flow –Greater standardization throughout form –Improved sampling instructions –More consistency between form, instructions, and the commodity manual –“Intermodal” checkbox –3PL questions on 4 th quarter form Electronic spreadsheet response option

11 Issues - 3PLs Many companies outsource part or all of their logistics operations These Third Party Logistics (3PL) providers are not in-scope to the CFS

12 3PLs - Example From an SEC filing: Company A sells its warehouse to Company B, a real estate investment company Company B in turn leases the warehouse to Company C Company C will provide warehousing and distribution services for Company A

13 Sample Design Features: Three stages of sampling Sample size of ~100,000 establishments Primary strata based on geography and industry Additional stratification based on size Special HAZMAT strata Special auxiliary strata

14 Geographic Strata 123 primary geographic strata –73 metropolitan area strata –50 balance of state strata Some metropolitan areas are split by state boundaries For 2007, ten metropolitan areas were added.

15 Geographic Strata

16 Industry Strata Up to 45 industry strata within each geographic area –Mining (3 industries) –Manufacturing (21 industries) –Wholesale (18 industries) –Non-store Retail (1 industry) –Retail fuel oil dealers (1 industry) –Publishers (1 industry)

17 Special HAZMAT Strata Used 2002 CFS data to identify 6-digit NAICS industries associated with six groups of HAZMAT shipments. –Ammonium nitrate –Ethanol –Explosives –Hydrogen –Toxic by inhalation –All other hazardous materials

18 Special HAZMAT Strata

19 Auxiliary Strata For auxiliaries that responded to the Advance survey (shippers only): –123 strata (one for each geographic stratum) –Combined NAICS 4931 and For non-responding auxiliaries: –1 national stratum for 4931 (warehouses) –1 national stratum for (management offices)

20 Summary of Stratification Sample stratification summary

21 Design Constraints Sample size of about 100,000 establishments CV of about 1.5% for each primary stratum Maximum first-stage (establishment) weight of 100

22 Sample Sizes Considered three designs: –Primary stratum CV = 1.5%, No national industry level CV constraint Note: Achieved national CV of 0.057% –Primary stratum CV = 1.6%, National industry level CV = 0.04% –Primary stratum CV = 1.7%, National industry level CV = 0.036%

23 Sample Sizes Summary of Sample Designs

24 Summary Recap of 2007 CFS changes: –Expanded industry coverage –Use of Advance survey to improve quality of frame data for auxiliaries –A redesigned questionnaire –Larger sample size –More detailed geography and industry stratification –National CV constraint on sample design

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