Survey of Motor Vehicle Use, Australia methodology

Vehicles were identified using information obtained from state and territory motor vehicle registration authorities as part of the annual ABS Motor Vehicle Census (see Motor Vehicle Census, Australia (cat. no. 9309.0)). The Motor Vehicle Census (MVC) provides a snapshot of registered vehicles at 31 January each year. There were 19.5 million vehicles identified from the MVC at 31 January 2019. These vehicles provided the population of vehicles, or survey frame, for the 2020 Survey of Motor Vehicle Use (SMVU).

The scope of the survey comprised all vehicles registered with a motor vehicle authority for road use during the 12 months ended 30 June 2020. Not included were caravans, trailers, tractors, plant and equipment, vehicles belonging to the defence services and vehicles with diplomatic or consular plates. Where they were registered as such, vintage and veteran cars were also excluded from the survey. Unregistered vehicles were out of scope.

For the 2020 SMVU, a sample of 16,180 vehicles was selected for inclusion in the survey. The survey sample consisted of passenger vehicles (18.0%), motor cycles (5.0%), freight vehicles (65.9%), buses (8.1%) and non-freight carrying trucks (3.0%). The sample size was chosen to give a suitable level of reliability for estimates of total distance travelled and tonne-kilometres travelled for each state/territory of registration by type of vehicle category over the survey period.

Vehicles were selected for one of three data collection periods, each 4 months in duration.

Owners of vehicles selected in the survey were asked to complete two questionnaires, either paper or web, tailored to their vehicle type. The first, at the beginning of the survey period, asked for selected vehicle characteristics and the vehicle odometer reading. Owners were also advised they would receive a follow up questionnaire at the end of the period, with examples of the main items included. The second questionnaire requested details about the use of the vehicle over the four month period and a second odometer reading.

When questionnaires were returned to the ABS they were checked for completeness and accuracy and, where possible, follow-up contact was made with owners to resolve reporting problems. Where contact with owners could not be made, missing items on incomplete questionnaires were filled by using data from like vehicles for which data were obtained.

Where the selected vehicle owner had not owned the vehicle for the whole four month survey period, the usage details provided for the period of ownership were adjusted to give a four month equivalent. Where the vehicle was deregistered during the four month survey period, only usage up to the date of deregistration was included.

In addition, adjustments were made in the estimation process to account for the use of new motor vehicles registered after the survey population was identified, as well as the re-registration of other vehicles during this time. More information about these adjustments is provided in 'How the data is processed'.

Estimates from information reported in each four month collection period were produced and these were then aggregated into annual estimates relating to the use of vehicles during the period 1 July 2019 and 30 June 2020.

For this release of the SMVU, the information reported in each four month collection period between 1 July 2017 to 30 June 2018 and 1 July 2019 to 30 June 2020 have been individually aggregated to produce sub-annual estimates relating to the use of vehicles. Sub-annual estimates are available in the download tab and cover the following collection periods:

2018 Sub-annual estimates

• 1 July 2017 to 31 October 2017
• 1 November 2017 to 28 February 2018
• 1 March 2018 to 30 June 2018

2020 Sub-annual estimates

• 1 July 2019 to 31 October 2019
• 1 November 2019 to 29 February 2020
• 1 March 2020 to 30 June 2020

Non-sampling error covers the range of errors that are not caused by sampling and can occur in any statistical collection whether it is based on full enumeration or a sample. For example, non-sampling error can occur because of non-response to the statistical collection, errors or omissions in reporting, definition or classification difficulties, errors in transcribing and processing data and under-coverage of the frame from which the sample was selected. If these errors are systematic (not random) then the survey results will be distorted in one direction and therefore will be unrepresentative of the target population. Systematic errors result in bias.

A number of indicators of possible non-sampling error are outlined below.

Imputation is the process whereby a value is generated for missing data. Data may be missing for a particular data item (partial imputation), or for a unit which has not responded to the questionnaire (full imputation). For the SMVU, imputed values are based on responses for similar vehicles which were operating for the reference period.

Imputation introduces non-sampling error, and the contribution to estimates from imputed data provides one measure of the reliability of the estimates. As for previous surveys, the need for imputation of unanswered items on the returned questionnaires remained quite high. The tables below show the percentage contribution to the estimates from both partial and full imputation.

An important factor that affects non-sampling error is the response rate. The ABS makes all reasonable efforts to maximise response rates. For the SMVU, mail reminders and telephone follow-up were used to attempt to contact non-responding vehicle owners. Usable responses were received from 79% of all of the selections for 2020, comprised of 76% from registered vehicles and 3% from unregistered vehicles, out of scope and duplicates.

After removing those vehicles that had been found to be deregistered or out of scope, the response rate for the 2020 SMVU was 78.5%.

Response rates for each State and Territory, and for each vehicle type, are shown in the following tables:

For the SMVU, it is assumed that the characteristics of non-responding vehicles are the same as for like responding vehicles. Non-response has the potential to cause non-response bias, which occurs if the usage patterns of the non-responding vehicles differ from those of the responding vehicles. For example, the lowest response rate achieved by vehicle type was for motor cycles (76%). 

A population or survey frame of 19.5 million vehicles was identified on 31 January 2019 using information obtained from the state and territory motor vehicle registration authorities, as part of the annual ABS Motor Vehicle Census (MVC) (cat. no. 9309.0).

The reliability of this frame in providing an accurate number of vehicles in scope of the survey is indicated by the number of duplicate vehicle registrations, vehicle de-registrations prior to frame extract, and out-of-scope vehicles identified. For 2020, approximately 0.2% of the total frame were identified as such. This indicates the frame was reliable in terms of providing an accurate number of registered vehicles in Australia.

Another indicator of frame quality is the number of units identified as in scope with different characteristics compared to what was recorded on the frame. For the SMVU, this can arise when respondents indicate an alteration has been made to the vehicle body, resulting in a different body type to that recorded on the frame. These changes can happen during the time-lag between finalising the frame and collection of SMVU data (between 5 and 17 months). Vehicle classification anomalies can also result from data supplied by state and territory vehicle registration authorities.

An assessment of vehicle classification anomalies from 2020 data shows that while there was no bias towards specific states or territories, there were marked discrepancies for some vehicle types. For vehicles on the frame that were listed as non-freight carrying trucks, 21.5% were found to be other vehicle types and 13.5% of vehicles listed as buses were found to be other vehicle types. This issue was not significant for other vehicle types on the frame.

The survey is comprised of three independent samples, with a different sample used for each four month period in the overall 12 month survey period. Estimates from each of these samples are aggregated and adjusted for new motor vehicles and re-registrations of vehicles to produce an annual estimate.

Sub-annual estimates were created using the three independent samples employed in the compilation of the annual survey. Estimates were then aggregated separately from each other rather than together. As with the annual estimates, each of the sub-annual level estimates have been adjusted for new motor vehicles and re-registrations of vehicles.

The SMVU aims to measure the use of all vehicles registered during the reference year. Because selections are taken from vehicles registered some time before the beginning of each collection period, adjustments are made to account for the change in size of the registered motor vehicle fleet since the population frame was created. For the 2020 SMVU, the frame was created on 31 January 2019. These adjustments involved two categories:

• re-registrations - older vehicles that are returning to the registered vehicle fleet after a period of de-registration, and
• new motor vehicles - vehicles which have not been previously registered.

For the sub-annual estimates, the adjustment for re-registrations has been applied in line with the annual estimates. However, adjustments to account for new motor vehicles have been applied differently to account for the different time periods of the three samples. As a result of the difference in application of this adjustment the sub-annual estimates will not total to exactly match the annual estimates.

These activities occur continuously and the adjustments are made to account for the registrations that are estimated to have been added to or removed from the registered vehicle fleet between the population frame date and the end of the reference period. The adjustment process also accounts for de-registrations. This means it is possible for the re-registration factor to be negative.

Some providers may report nil use for the 4 month reference period in which they were selected. Nil use vehicles are registered vehicles that report no travel during that specific reference period. Nil use vehicles are included in the survey as their reported nil use is representative of other vehicles in the population. Vehicles may have nil use due to factors such as seasonal usage, mechanical faults or economic conditions. Where a provider gives a nil use response, a follow-up phone call is used to check the veracity of the response.

The following core estimates of motor vehicle use are produced for each release:

• Number of vehicles
• Kilometres travelled
• Fuel consumed
• Tonne kilometres travelled
• Tonnes carried

Data cubes containing all tables for this publication in Excel spreadsheet format are available from the Data download section of the main publication. The spreadsheets present tables of estimates and averages, and their corresponding relative standard errors (RSEs).

Any discrepancies between totals and sums of components in this publication are due to rounding.

Motor Vehicle Use data is available as a microdata product through TableBuilder, an online tool for creating tables and graphs.  Further information about this service can be found here Microdata Entry Page

Most tables in this publication include statistics presented as averages. The denominator used in calculating these averages varies depending on the characteristics of interest. The method of calculating each average is noted in the table where it is presented. As the denominators used to calculate each average are different it should be noted that the averages along a table row cannot be used to derive the total column entry for that row.

Survey estimates of the numbers of vehicles, by vehicle type for SMVU are not fully comparable with ABS Motor Vehicle Census data (see Motor Vehicle Census, Australia (cat. no. 9309.0)). The main differences are:

• Survey estimates of the numbers of vehicles relate to the average number of vehicles registered for road use during the period 1 July 2019 to 30 June 2020, not to the number of vehicles registered at a specific date, as is the case for the Motor Vehicle Census.
• Characteristics of the vehicle reported in the survey information may differ from those recorded by the motor vehicle registries.

Special care should be given when interpreting the survey estimates of the number of vehicles for the sub-annual estimates. The survey is designed for an annual output of the average number of vehicles registered for road use.

This publication includes estimates of vehicle use for earlier years. However, it should be noted the survey was designed to produce reliable estimates of key data items for a point in time, not for year-to-year changes. Estimates of movement over time are subject to high sampling error and care should be taken in drawing inferences from these comparisons.

The sub-annual estimates included in this publication are based on a design to produce reliable estimates of key data items for a point in time for an annual output, not for four month to four month changes.  It is likely that the sub-annual estimates are subject to a higher sampling error due to the smaller sample sizes.

This release will be the first time sub-annual estimates will be published.

The Survey of Motor Vehicle Use, 2020 will be the final release of this publication.