Canadian Vehicle Survey 2007 Summary Report

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Annex B. Scope and methodology of the Canadian Vehicle Survey

This section summarizes the methodology used in the Canadian Vehicle Survey, conducted by Statistics Canada on behalf of Transport Canada and Natural Resources Canada (NRCan) in 2007. More information is available in the Canadian Vehicle Survey: Annual 2007 (Revised), produced by the Transport Division of Statistics Canada.¹⁴

General description

The CVS is a voluntary survey of vehicles that is conducted quarterly. The survey design also allows for calculation of annual estimates based on the data collected during the four quarters.

The survey population consists of all motor vehicles registered in Canada at any time in 2007 that have not been scrapped or salvaged. Buses (since 2004), motorcycles, off-road vehicles (e.g. snowmobiles) and special equipment (e.g. cranes, snowploughs) are excluded from the registration lists used in the sample.

The survey population is derived from the vehicle registration lists sent by the governments of the 10 provinces and three territories to Statistics Canada three months before the reference period. This population differs slightly from the population of interest, as vehicles that were registered less than three months before the quarter began, or during the quarter, are not included in that quarter’s sample (the sample for each quarter is derived from the population of the preceding quarter).

The registration lists received by Statistics Canada undergo a rigorous preparation procedure:

• Out-of-scope vehicles are removed.
  
  
• Vehicles with expired registration are removed.
  
  
• Records with duplicate Vehicle Identification Numbers within a given list are removed, leaving the one updated most recently.
  
  
• Records with irregular data are verified.

The most recent set of prepared lists is used to select the sample for each quarter. These sets of vehicle lists and the days within the respective quarter constitute the survey population.

Survey design

The CVS uses a two-stage sample design. A sample of vehicles is selected in the first stage, and a sample of consecutive days within the quarter is selected in the second stage.

In the first stage, all vehicles from the survey population are stratified into 78 strata according to vehicle type, jurisdiction and vehicle age. Then a systematic sample of vehicles (first-stage sample) is selected from the survey population to spread the sample over all regions.

In the second stage, a first reporting day within the quarter is randomly assigned to each vehicle that had been selected in the first stage. Within each stratum, the first reporting day is evenly spread over the quarter to ensure a uniform number of responses over time and for each day of the week. This step is not applied to the vehicles registered in the three territories because only odometer readings are collected.¹⁵

The sample from the 10 provinces consisted of 26 987 vehicles for the four quarters of 2007. The sample from the three territories consisted of 10 988 vehicles.¹⁶ Table B-1 shows the number of vehicles sampled in the provinces and territories in 2007 by type of vehicle.

Table B-1 Number of vehicles in sample by jurisdiction and vehicle type

Jurisdiction	Light vehicles	Medium trucks	Heavy trucks	Total
	Number of vehicles in sample by jurisdiction
Newfoundland and Labrador	926	221	204	1 351
Prince Edward Island	543	147	180	870
Nova Scotia	1 105	278	269	1 652
New Brunswick	1 182	272	228	1 682
Quebec	3 476	542	470	4 488
Ontario	5 611	618	661	6 890
Manitoba	1 119	291	336	1 746
Saskatchewan	1 337	400	360	2 097
Alberta	1 917	590	533	3 040
British Columbia	2 224	614	333	3 171
Total for provinces	19 440	3 973	3 574	26 987
Yukon	1 576	1 423	784	3 783
Northwest Territories	3 352	737	917	5 006
Nunavut	2 528	231	145	2 904
Total for territories	7 456	2 391	1 846	11 693
Total for Canada	26 896	6 364	5 420	38 680

Data collection

Data collection for the vehicles sampled is conducted differently in the provinces than in the territories. In the provinces, the registered owners of the sampled vehicles are contacted for a Computer-Assisted Telephone Interview (CATI). During the CATI, the following information is collected about each sampled vehicle:

• vehicle type
  
  
• fuel type used
  
  
• distance driven the previous week
  
  
• anticipated vehicle use during the following six weeks
  
  
• current odometer reading
  
  
• vehicle maintenance
  
  
• household characteristics

Respondents are then asked to complete a trip log. If they agree, the trip log is mailed to them. There are two types of logs: one for light vehicles and one for medium and heavy trucks.

Respondents receiving a light-vehicle log are requested to record information for 20 consecutive trips made in the selected vehicle, beginning on the assigned first reporting day. Respondents have to record a new trip each time the driver enters the vehicle or a passenger enters or exits the vehicle.¹⁷

Respondents receiving a heavy-vehicle log (medium and heavy trucks) are requested to record information for all the trips made in the selected vehicle over the assigned seven days. A new trip begins if there is a stop made of over 30 minutes, if the driver changes, if the reason for the trip or the use of the vehicle changes, if the truck configuration is modified or if the truck goes from full to empty or the reverse.

The following information is recorded for each trip:

• start-and-stop dates and times
  
  
• start-and-stop odometer readings
  
  
• starting point and destination (light vehicles) or trip purpose (heavy vehicles)
  
  
• number and age group of passengers (light vehicles) or number of passengers at the start and end of the trip (heavy vehicles)
  
  
• gender and age group of the driver
  
  
• total cost, per unit cost and amount of fuel purchased
  
  
• distance travelled on roads with a posted speed limit of 80 (km/h) or more
  
  
• truck configuration (heavy vehicles)
  
  
• dangerous goods (heavy vehicles)

Since 2004, when NRCan became co-sponsor of the CVS, respondents have been asked to continue recording fuel purchases until they reported two fill-ups or five purchases or until the 28-day reporting period was over. Less information is collected in the territories. Statistics Canada sends a questionnaire at the beginning of the quarter and one at the end, asking for an odometer reading so the distance travelled during the quarter can be identified. Information is also collected on the vehicle’s status (still owned, sold or scrapped), body style and type of fuel used.

Data edit and imputation

Once all the necessary information for the survey has been collected, Statistics Canada conducts a series of computerized and manual verifications to ensure that the records are consistent and that there are no errors as a result of data capture.

Missing values and data found to be in error are imputed by another automated system using different imputation rules depending on the vehicle, available information and type of data to be imputed. For example, data can be imputed based on responses to other questions or by using data from similar vehicles. The imputed data are examined again for completeness and consistency.

Response rate

Statistics Canada defines the CVS response rate as the number of vehicles for which the respondents have provided full or partial answers to the questions concerning vehicle-kilometres only, divided by the total number of vehicles in the sample. Tables B-2a and
B-2b show the response rates obtained for each quarter by vehicle type.

Table B-2a Response rate for the CVS – All provinces

Quarter	Light vehicles	Medium trucks	Heavy trucks
	Percent
Quarter 1	64.8	63.9	65.5
Quarter 2	60.0	58.8	60.1
Quarter 3	61.2	59.2	55.2
Quarter 4	58.3	55.0	56.7
Annual	61.0	59.2	59.4

Table B-2b Response rate for the CVS – All territories

Quarter	Light vehicles	Medium trucks	Heavy trucks
	Percent
Quarter 1	14.8	9.6	10.8
Quarter 2	13.7	10.9	9.7
Quarter 3	14.0	13.6	12.6
Quarter 4	12.5	7.2	9.5
Annual	13.7	10.2	10.6

The response rate for the fuel component of the CVS is lower than the response rates in the preceding tables. While the exact response rate for this part of the survey is not available, Table B-3 shows that 2 739 respondents reported their fuel purchases for 26 987 vehicles sampled in the provinces in 2007. Therefore, the data on fuel consumption have a high imputation rate, which helps explain the lower quality of fuel consumption estimates in this report.

Table B-3 Number of respondents reporting their fuel purchases (all provinces and vehicle types)

Number of purchases	Number of respondents
1	841
2	1 019
3	292
4	177
5	409
6	1
Total	2 739

Estimates and quality indicators

Estimates are based on the principle that each vehicle in the sample represents a certain number of vehicles in the population of interest. A sample weight is therefore assigned to each vehicle in the sample, and the purpose of the final set of weights is to reflect as closely as possible the characteristics of the vehicle population during the reference period. All estimates for 2007 presented in this report were produced using an estimate module developed by Statistics Canada.

This module also calculates the coefficient of variation (CV), reflecting the quality of each estimate. The CV takes into account variability due to sampling and variability due to non-response and imputation. For example, a variance due to relatively high imputation has a negative effect on the quality of fuel consumption estimates. Estimates with a CV of more than 35 percent are not reliable enough to be published. Table B-4 describes the indicators used in this report to describe the quality of estimates.

Table B-4 Indicators for coefficients of variation

Coefficient of variation	Indicator of quality	Quality of estimate
Less than 5.0%	A	Excellent
5.0% to 9.9%	B	Very good
10.0% to 14.9%	C	Good
15.0% to 19.9%	D	Acceptable
20.0% to 34.9%	E	Use with caution
35.0% or over	F	Too unreliable to be published

For more information on the methodology used in the Canadian Vehicle Survey, contact the Transport Division, Statistics Canada, at

Transport Division
Statistics Canada
100 Tunney’s Pasture Driveway
Ottawa ON K1A 0T6
Tel.: 1-866-500-8400
E-mail: transportationstatistics@statcan.ca.

¹⁴ Statistics Canada. Canadian Vehicle Survey: Annual. Catalogue No. 53-223-XIE.www.statcan.ca/bsolc/english/bsolc?catno=53-223-X.

¹⁵ Less information is collected in the territories because respondents there are asked to participate in several surveys a year.

¹⁶ A larger sample in the territories enables Statistics Canada to compensate for a lower response rate in these jurisdictions.

¹⁷ This definition has been used as of the first quarter of 2004 and is different from that used in previous versions of the CVS.

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