Asphalt Roofing

Detailed information for March 2005

The monthly survey, Asphalt Roofing, measures quantities of selected asphalt roofing products that are produced and shipped by Canadian manufacturers including destination of shipments by province and exports.

Data release - May 3, 2005

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

Description

This survey measures, on a monthly basis, the quantities of selected asphalt roofing products that are produced and shipped by Canadian manufacturers and the destination of shipments by province and exports.

The quantities of asphalt roofing products produced and shipped are used as an indicator of the economic condition of this industry and trends in the housing market, as an input to Canada's Gross Domestic Product and as an input into macro- and micro-economic studies to determine market shares and industry trends. Data are used by the business community, trade associations (including the Canadian Asphalt Shingle Manufacturers' Association) federal and provincial departments and international organizations.

Reference period: Month

Collection period: Each month

Subjects

• Construction
• Construction materials
• Manufacturing
• Petroleum and coal

Data sources and methodology

Target population

The target population for this survey includes manufacturers in Canada of asphalt roofing products as defined in the Standard Classification of Goods (SCG), that report these products to the Annual Survey of Manufacturing and Logging Industries or ASML (record number 2103). This means that estimates from this monthly survey do not cover the entire universe of Asphalt roofing producers in Canada because the ASML does not survey all businesses. Instead, the ASML uses administrative data to cover the small and medium-sized establishments. These manufacturers are not part of this monthly survey.

Instrument design

The questionnaire was developed in collaboration with the Canadian Asphalt Shingle Manufacturers' Association in order to fulfill their needs. Regular dialogue is maintained with the association and the respondents, and every effort is made to ensure that the questions asked are relevant and can be answered by the manufacturers.

Sampling

This survey is a census with a longitudinal design.

This methodology does not apply.

Data sources

Responding to this survey is mandatory.

Data are collected directly from survey respondents.

Data are collected each month from survey respondents using a mail-out / mail-back process. Data capture and preliminary editing are performed simultaneously to ensure validity of the data. Businesses from whom no response has been received or whose data may contain errors are followed-up by telephone or fax.

Under normal circumstances, data are collected, captured, edited, tabulated and published within 4 weeks after the reference month.

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

Error detection

In order to detect errors and internal inconsistencies, automated edits are applied to captured data to verify that totals equal the sum of components and that the data are consistent with the previous month's data. Data that fail the edits are subject to manual inspection and possible corrective action.

In addition, subject matter experts analyze the data at a more aggregate level to detect and verify any large month-to-month or year-over-year changes for the industry.

Imputation

Missing data for the current month are imputed automatically by applying to the previous month's value, the month-to-month change observed for the same period in the previous year, for the unit in question. However, an option exists for analysts to manually override this imputation with a better estimate based on pertinent knowledge about the industry or the business.

Quality evaluation

Survey results are analyzed to ensure comparability with patterns observed in the historical data series and the economic condition of the industry. Information available from other sources, such as the Monthly Survey of Manufacturing (record number 2101), the Building Permits survey (record number 2802), the media, other government organizations, and industry associations, are also used in the validation process.

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.

Confidentiality analysis includes the detection of possible direct disclosure, which occurs when the value in a tabulation cell is composed of a few respondents or when the cell is dominated by a few companies.

Data accuracy

The methodology of this survey has been designed to promote data accuracy. Since data are collected from all Canadian producers of asphalt roofing products as defined in the target population, the resulting estimates are not subject to sampling error. However, the results are still subject to the non-sampling errors associated with coverage, non-response, inaccurate reporting, and processing. Errors relating to coverage and non-response can be measured. All attempts are made to control inaccurate reporting and processing errors.

Coverage errors
There is a degree of under-coverage (referred to as coverage error) in the survey results as there is generally a lag between the time a new business comes into existence and when it is included in the universe of this sub-annual survey. This is due to the fact that the list of companies surveyed is derived from the latest available survey results of the ASML which are not available until 15 months after the reference period.

This error is kept at a minimum by also using advance information from the ASML, feedback from the MSM and other sources such as the Canadian Asphalt Shingle Manufacturers' Association, trade journals and newspaper articles, to identify new survey units.

Non-response errors
Some respondents may be unable to provide data for numerous reasons (i.e. fire, theft, strike, economic hardship, etc.), while others may be late in responding. To minimize non-response, delinquent respondents are followed up rigorously by phone or fax. Data for non-responding units are imputed using industry trend and other related information. Data are revised at a later date, if completed questionnaires are received after the end of a collection cycle.

Non-response error is calculated using the number of non-responses in the year divided by the number of total expected responses in the year.

Inaccurate response
Inaccuracy may result from poor questionnaire design or an inability on the part of respondents to provide the requested information or from misinterpretation of the survey questions. To reduce such errors the format and wording in the questionnaire are reviewed from time to time and modified based on feedback from survey respondents and data users. Respondents are also reminded of the importance of their contribution and of the accuracy of reported information.

Processing errors
These errors may occur at various stages in the processing of survey data such as data entry, verification, editing and tabulation. Data are examined for such errors using automated edits along with an analytical review by subject matter experts. Several checks are performed on the collected data to verify internal consistency and comparability over time.