Wholesale Services Price Index (WSPI)
Detailed information for second quarter 2016
The purpose of this survey is to collect and compile data to measure the monthly change in the movement of the price of wholesale services. These prices are combined and chained to form a price index. The estimates are produced on a quarterly basis.
Data release - November 17, 2016
The purpose of this survey is to collect and compile data to measure the monthly change in the movement of the price of wholesale services. These prices are combined and chained to form a price index. The estimates are produced on a quarterly basis. These price data are combined to estimate a price index for the wholesale services sector that can be joined with other business service indexes to provide better estimates of real output and productivity, monitor inflation and feed an important research agenda at Statistics Canada.
These indexes are a part of the Services Producer Price Index program (SPPI) at Statistics Canada.
The SPPI program develops and produces price indexes for a wide range of business service categories. This initiative fills an important data gap in the area of economic statistics and has resulted in a more comprehensive set of service price indexes. It also allows Statistics Canada to produce more accurate estimates of real value added of the Gross Domestic Product and changes in productivity.
Reference period: The time period for which the WSPI equals 100; currently this is the year 2013.
Collection period: Collection takes place during the quarter following the reference quarter.
- Prices and price indexes
- Retail and wholesale
- Service price indexes
Data sources and methodology
The target population consists of all statistical establishments on the Business Register (BR) primarily engaged in wholesaling and that are classified to NAICS 41 - Wholesale Trade under the North American Industry Classification System (NAICS), excluding Business-to-business electronic markets, agents and brokers.
Pricing methodologies and questionnaire design were researched and based on internationally accepted practices and improved through consultation and collaboration with industry experts and the Questionnaire Design and Research Center at Statistics Canada.
This is a sample survey with a longitudinal design.
The frame is part of Statistics Canada's Business Register classified to the wholesale sector (NAICS=41). The population is stratified by 5-digit NAICS and by size based on revenue. The sample is allocated to strata by revenue and selected based on probability proportional to size using Sequential Poisson sampling. The sampling unit is establishment.
Data collection for this reference period: 2016-08-05 to 2016-10-04
Responding to this survey is mandatory.
Data are collected directly from survey respondents.
Following sample selection, new survey participants (respondents) are introduced to the survey through telephone calls. During this initial phase of data collection, respondents are guided through the process of selecting representative products for which prices and their characteristics (specifications) will be monitored. This process typically spans several collection cycles until respondents become conversant with the survey.
In subsequent cycles, monthly data are collected on a quarterly basis via electronic questionnaire and by mail out, mail back paper questionnaires, while telephone communication (Computer Assisted Telephone Interviewing) is used for non-response and data follow-up. Several follow-up contacts can be made including sending out a reminder fax or letter in order to collect data.
Information about the time it takes respondents to complete the survey questionnaire is collected and monitored closely. Currently, it takes respondents an average of 30 minutes to complete the survey.
View the Questionnaire(s) and reporting guide(s) .
Error detection is conducted both at the time of collection and during post collection processing, using a set of systematized error detection procedures to identify outliers and possible reporting anomalies. Records that fail these edits are reviewed for editing and correction when necessary or edit failure may trigger a follow-up with the respondent.
Non-response or missing prices are imputed using the averages of designated cells from within the same strata.
The price of the wholesale service is defined as the margin price, which is the difference between the average purchase price and the average selling price of a given product. It is not a wholesale selling price.
The Wholesale Services Price Index (WSPI) uses establishment revenues and industry gross margins as its weighting sources. Establishment revenue data are derived from the Business Register and the industry gross margins from the Annual Wholesale Trade Survey (record number 2445). The weight reference period is currently 2013. Weights are updated during a sample/basket update which typically occurs every 5 years. The last update occurred with the release of second quarter 2016 data.
Estimates are produced by calculating a weighted average of price relatives by industry, which are chained together to form an index series. The WSPI is a Laspeyres chain linked index, available at the Canada level only.
Linking of indexes
With the introduction of a new basket, historical estimates are linked to the new basket by maintaining the same historical monthly changes. This is done by calculating a link factor for each index series as the ratio of the new basket index series (2013=100) in the overlap period to the historical index series (2008=100). This link factor is applied to the historical index series to bring it up or down to the level of the new index.
The overlap period for WSPI is currently December 2015.
The survey methodology was designed to control for errors and to reduce their potential impact on estimates. The data is subject to collection and processing validations on key variables and most non-essential data. Analysis at the index level is also performed at various stages of aggregation. Qualitative assessment is done using an internationally developed framework for services producer price indexes that considers program elements such as the type of price being used, timeliness and relevance.
Statistics Canada is prohibited by law from releasing any information it collects that 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.
In order to prevent any data disclosure, confidentiality analysis is done using the Statistics Canada Generalized Disclosure Control System (G-Confid). G-Confid is used for primary suppression (direct disclosure) as well as for secondary suppression (residual disclosure). Direct disclosure occurs when the value in a tabulation cell is composed of or dominated by few enterprises while residual disclosure occurs when confidential information can be derived indirectly by piecing together information from different sources or data series.
Revisions and seasonal adjustment
Data for the most recent quarter are preliminary. The previous quarter of the series is subject to revision. The series is also subject to an annual revision released with second quarter data of the following reference year. The indexes are not seasonally adjusted.
The statistical accuracy of this index depends on price and weight data obtained from sample surveys. Each type of input data is subject to its own errors. Processing procedures for editing and imputation are in place to ensure the quality of data. Consequently, the aggregate indices at all levels are considered to be statistically reliable.
The survey achieves about a 75% response rate and uses a survey methodology designed to control errors and reduce their effect on estimates. However, the survey results remain subject to sampling and non-sampling error.
Sampling errors occur when observations are made only on a sample and not on the entire population. All other errors that arise from the various survey phases are referred to as non-sampling errors. For example, non-sampling errors can occur when a respondent provides incorrect information or does not answer certain questions; when a unit in the target population is omitted or covered more than once; when an out of scope unit is included by mistake or when errors occur in data processing, such as coding or capture errors.
A systematized imputation process is used to impute for the non-response portion of the sample, achieving an effective 100% coverage. Non-response bias is also minimized during the same process.