MONTANA AGRICULTURAL STATISTICS 87 



STATISTICAL METHODS 



GENERAL 



The Montana Crop and Livestock Reporting Service has two primary objeaives: 



1. To develop accurate, reliable agricultural statistics 

 1 To move those statistics to users as rapidly as possible 



Data colleaion to achieve these objectives, in most cases, involves sample surveys of farmers and ranchers, 

 grain companies, feed mills, seed dealers, retail stores, and many other agricultural enterprises. 



From data reported by these many sources, statisticians, using all available statistical tools, generate State totals 

 forming official USDA estimates. Cooperation of USDA and the Montana Department of Agriculture provides 

 resources for breaking State totals into crop reporting districts and counties. 



Montana agricultural statistics are available in two dimensions — State estimates and county or crop reporting 

 district estimates. 



STATE ESTIMATES 



The U.S. Department of Agriculture is required by law to provide National crop and livestock statistics and 

 statistics for each major producing State. 



For many years and to a considerable extent today, mailed non-probability surveys served as the backbone of 

 data gathering. However, probability sampling, a more sophisticated sampling procedure, is being incorporated as 

 funds and applied technology allow. Some types of probability sampling used in Montana are Area Frame Sampling, 

 List Frame Sampling, and Multiple Frame Sampling. Sampling farm operators in a specifically outlined geographic 

 area is known as Area Frame Sampling, while sampling a list of all known producers of a specific commodity is 

 known as List Frame Sampling. A technique called Multiple Frame Sampling takes advantage of the attributes of 

 both the Area and List samples. Area Frame Sampling is used in Montana for a number of acreage and livestock 

 items and Multiple Frame Sampling is used for estimating the cattle inventory and calf crop. 



The concept of probability sampling is maintained in all three types of sampling. Data collection therefore 

 involves personal enumeration and telephone or personal followup for all non-respondents to mail question- 

 naires. These probability surveys are expensive on a per sampling unit basis but yield State results that have greater 

 precision and allow measurement of the sampling error. 



The Number 1 grain crop in Montana, wheat, is measured by objective yield procedures. Forecasts before 

 harvest incorporate plant counts, kernel and head counts,and weight. Sample fields are entered with permission of 

 growers, by enumerators in May, June, July, August, and September to take counts and measurements. After 

 harvest, gleaning provides estimated harvesting loss. 



COUNTY ESTIMATES 



Federal funding and regulations support State estimates for specific agricultural items that are important in 

 National totals. When additional items or geographic descriptions within States are needed, local funding is 

 required. To provide estimates by county for example, requires a much larger sample because each county must 

 have enough reports to provide a statistically sound basis for estimates. Without going into details of statistical 

 requirements and concepts, it is sufficient to point out that if reporting units display the same variation within 

 county as they do within the entire State, then a sample will be required in each county nearly as large as the State 

 sample. 



Large mailings are needed to place enough questionnaires in the hands of producers in each county. If 

 response is low in some counties, telephone followup is needed to secure additional reports. Also, information for 

 minor crop acres is secured from informed people in each county — such as county agents, ASCS personnel, etc. 

 County assessments and their change from year to year are a reliable indicator for livestock estimates by counties. 



The Montana Department of Agriculture and Wheat Research and Marketing Committee provide funds for 

 local agricultural data. 



CHECK DATA 



In addition to producer surveys, check data are colleaed from the marketing channels to verify or supplement 

 the grower survey data. These data become available — usually long after harvest and are used to establish final 

 production and marketing figures. 



The final estimate is arrived at when all grower survey data and marketing data (check data such as: handler or 

 processor receipts, slaughter, and market shipments) have been analyzed. These data then become the statistical 

 history against which current forecasts and estimates are viewed. 



