Survey of Commercial Stocks of Corn and Soybeans (CSCS)

Detailed information for December 31, 2003

This survey collects data on commercial elevator stocks of corn and soybeans and the industrial use of corn.

Data release - February 5, 2004

• Questionnaire(s) and reporting guide(s)
• Description
• Data sources and methodology
• Data accuracy

Description

This survey collects data on commercial elevator stocks of corn and soybeans and the industrial use of corn. The estimates produced are used in national supply-disposition analyses to verify production and farm stocks. The data are also used by Agriculture and Agri-Food Canada and by grain analysts in the public and private sectors.

Reference period: Industrial use of corn: September to December; September to March; September to August. Stocks are as of the last day of the reference period.

Collection period: Collected during the two weeks following the reference period.

Subjects

• Agriculture and food (formerly Agriculture)
• Crops and horticulture

Data sources and methodology

Target population

The target population consists of grain elevators, processors, and exporters with stocks of corn for grain and soybeans, as well as industrial users of corn, in Ontario and Quebec.

This is a sample of all known companies that maintain stocks, as determined by the Ontario Ministry of Agriculture, Food and Rural Affairs. It excludes elevators licensed by the Canadian Grain Commission. The total sample size for this survey is approximately 95-100 units.

Instrument design

The questionnaire was developed by subject matter specialists through consultation with industry experts. Questions will be changed, added or removed as the need arises. Required changes are usually identified through such means as subject matter specialist research and changes in market trends.

Sampling

This is a sample survey with a cross-sectional design.

A registry of elevators maintained by the Ontario Ministry of Agriculture, Food and Rural Affairs is updated and provided to Statistics Canada annually. A few elevators are located in Quebec but most are located in Ontario. The survey frame consists of about 250 elevator company headquarters and contains information on the elevator capacity, type of elevator (industrial user, feed manufacturer and country elevator) and contact information. Any elevators licensed by the Canadian Grain Commission are removed from the frame. The frame selected for the December survey is also used for the March and August surveys. The frame is then stratified by type of elevator and by capacity. Industrial users and feed manufacturers are grouped in a take-all stratum. The rest of the sample is selected randomly within each of the four strata. The sample comprises of approximately 100 elevators.

Data sources

Responding to this survey is mandatory.

Data are collected directly from survey respondents.

The data are collected through a mail-out/mail-back process, while providing respondents with the option of telephone or other electronic filing methods. Follow-up procedures are applied when a questionnaire has not been received after a pre-specified period of time: respondents are phoned or sent a facsimile or e-mail to remind them to send their questionnaire in order to reach the survey target response rate.

View the Questionnaire(s) and reporting guide(s).

Error detection

There are three main edits. The first checks that the company owned stocks and the stocks held for farm accounts add to the total stocks. The second compares the reported stocks of each elevator to its capacity to ensure the stocks are less than the capacity. The third selects elevators that were in the sample in the previous year and compares the stocks from the previous year with the current year. Changes of 30 per cent up or down are selected for further verification.

Changes in the industrial use of corn are reviewed manually by analysts with knowledge of industry and supply-disposition trends.

Imputation

Every attempt is made to obtain reports from the small number of industrial users. Missing data are imputed manually using historical records for the same elevators or using trends from similar units reporting in the current year.

Estimation

The stock estimates produced from the survey using weights and pair-change ratios are further refined using farm and national supply-demand tables.

The corn industrial use data are compared to the same period of previous crop years. Trends in pricing of substitutable commodities and in available grain supplies also help in selection of the point estimates.

Quality evaluation

Supply-demand analyses are used in combination with industry analyses. An annual review of the estimates is conducted by methodologists.

Disclosure control

Statistics Canada is prohibited by law from releasing any information it collects which could identify any person, business, or organization, unless consent has been given by the respondent or as permitted by the Statistics Act. Various confidentiality rules are applied to all data that are released or published to prevent the publication or disclosure of any information deemed confidential. If necessary, data are suppressed to prevent direct or residual disclosure of identifiable data.

Data accuracy

While considerable effort is made to ensure high standards throughout all stages of collection and processing, the resulting estimates are inevitably subject to a certain degree of non-sampling error. Non-sampling error is not related to sampling and may occur for many reasons. For example, non-response or incomplete responses are important sources of non-sampling error. Population coverage, differences in the interpretations of questions and mistakes in recording and processing data are other examples of non-sampling errors.

Non-sampling errors are controlled through a careful design of the questionnaire, the use of a minimal number of simple concepts, consistency checks and automated edits. Measures such as response rates are used as indicators of the possible extent of non-sampling errors. The response rate for this survey ranges from 90-95%.

Sampling error can be measured by the standard error (or standard deviation) of the estimate. The coefficient of variation (CV) is the estimated standard error percentage of the survey estimate. Estimates with smaller CVs are more reliable than estimates with larger CVs. The CVs for the total stocks are in the range of 3-4%. Generally any estimate with a C.V. value under 5% is considered to be of excellent quality.