Improving Crop Estimates by Integrating Multiple Data Sources (2017) / Chapter Skim
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Appendix A: NASS County-Level Survey Programs
Appendix A: NASS County-Level Survey Programs
Pages 111-122
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From page 111... ...
List samples are conducted in June, September, December, and March, with the survey content differing each quarter to capture the seasonality of agriculture: the June survey collects data on planted acres for spring-planted crops and acres harvested and to be harvested for spring crops and winter wheat; the September survey collects data on final harvested acres and production (or yield) of small grains; the December survey collects data on seeded acres of winter wheat (new crop)
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From page 112... ...
Thus, interviews for the September and December APS surveys capture end-of-season acreage and production data for small grains and row crops, respectively. Like the APS surveys, CAPS collects data shortly after harvest so that final production and yield are known, yet close enough to harvest so that memory bias is not an issue.
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From page 113... ...
The Row Crops APS and CAPS list frame samples are selected using a multivariate probability proportional to size (MPPS) sampling scheme in which the measure of "size" is determined by more than one item (see Bailey and Kott, 1997)
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From page 114... ...
The first is used in the estimation process for the Row Crops APS surveys at the state and national levels. The second is used to produce estimates for the combined Row Crops APS and CAPS surveys at the county level (both in composite estimators that use the JAS data)
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From page 115... ...
are direct expansions of the combined Row Crops CAPS and December Row Crops APS list records. Explicit formulae used by NASS may be found in Kott (1989)
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From page 116... ...
Subsequently, the composite estimates at the county level are ratio adjusted to the rounded ASD estimates. Enforcement of NASS rounding rules at the county level generates the official county-level totals.
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From page 117... ...
NASS verifies that estimates meet publication standards that must be met before any official estimate can be published. First, if the combined sample sizes realized for the CAPS and APS surveys include at least 30 positive reports of crop production, the county-level (or ASD-level)
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From page 118... ...
Because cash rent items pertain to the entire farm, including those portions lying outside the sampled tract, the survey weight for a record is the product of the original segment sampling weight from the area frame and the proportion of the farm residing within the segment boundaries (called the farm-to-tract ratio)
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From page 119... ...
based on the most recent Census of Agriculture. The Cash Rents Survey collects data on acres rented and cash rental rates or total dollars paid in rent for three land use categories: irrigated cropland, nonirrigated cropland, and permanent pastureland.
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From page 120... ...
Both models also include as covariates the National Commodity Crop Productivity Index from the Natural Resources Conservation Service (NRCS) , a yield index from NASS historical estimates, and the total value
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From page 121... ...
The NASS publication standard for the Cash Rents Survey is that there must be at least 30 positive reports of rent in the county, or if there are fewer responses, the sum of their corresponding unweighted acreage must account for at least 25 percent of rented acreage estimated. Estimates based on samples of fewer than 3 reports are automatically suppressed.
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