Discussion, Q2010 Cynthia Clark National Agricultural Statistics Service

2 Alternative to Probability Sampling Comes from the discipline of applied economics Applies to real world problems and is based on the intersection of : - economic theory - methods of analysis (econometrics) - history/institutions/judgment Describe the procedure used by the National Agricultural Statistical Service (NASS), a U.S. National Statistical Office

3 Methods of Analysis Economic Theory History Institutions Judgment Applied Economics Real World Problems Definition of Applied Economics

NASS Statistical Progra m Produces forecasts and estimates of agricultural production for crops and livestock Issues reports on agricultural commodity prices & expenditures Reports on farm numbers, employment, income and land use Provides data on costs of production 4

NASS Crop Forecasts and Estimates Surveys of farm operators Weekly report on crop progress Surveys of objective yield for crop using measurements of the commodity Administrative data from farm program payments or other “final data” Time series for yield of commodity Weather and precipitation data Days to frost 5

Estimation Process Data collected and analyzed at state level Statisticians provide best estimate of commodity for their state Data sent encrypted to HQ office where it is summarized Board of internal experts review the data in secure setting 6

Agricultural Statistics Board Review summarized data for survey – list, area, & multi-frame estimates Review objective yield models for number, size, weight Examine weather conditions Review survey procedures “Set” national & then state estimates 7

Release Procedures for Market Sensitive Data ASB “locked up” during review process No internet, phone, or other communication capabilities Press come into locked site one hour before announced release time No political summary until one hour after release Data received credibly by agricultural community 8

Concerns with Process Not reproducible Not transparent – not clear how estimates were derived No estimates of variability or bias released with the estimates Does not adhere to OMB Statistical Standards Directive 9

Difficulties in NASS Commodity Estimation NASS survey program has designed multiple estimates where some work for some commodities; some for other No criteria developed for estimate selection from program Non-surveyed variables are important in estimation of production 10

Where do we go from here?es? Continue as is Release survey estimates with coefficients of variation where possible (or other measures of error) Develop model based estimates bringing in covariates 11

Planned Approach Review program to determine where survey estimates can be released Examine measured sampling and nonsampling errors associated with those surveys & issue those relevant Include response and coverage rates and biases 12

Planned Approach (continued ) Develop model based estimates where covariates are needed Provide advance notice of methodology changes Bridge new estimates with past board estimates 13

14 Methods of Analysis Economic Theory History Institutions Judgment Applied Economics Real World Problems Definition of Applied Economics

New Process Move to estimation that acknowledges use of statistical process Based on surveys using random representative samples Manage survey processes to reduce nonsampling errors Measure relevant errors Provide clear documentation of process 15

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