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Method of Travel to Work
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Applicable to: Employed persons
Total number of categories: 237
More Detailed Description
Quality Statement - Method of Travel to Work (MTWP)
There are many aspects which can affect the quality of Census data; the following information should be considered when viewing data on Method of Travel to Work (MTWP).
This data was were captured automatically from check box responses on the form so the risk of processing error is minimal. Respondents were able to provide up to three responses, and a code was derived to reflect a single response or a combination of responses. However 95% of the data is made up of single responses, representing one mode of travel, eg train or bus. Sample checks of the data are undertaken to ensure an acceptable level of quality.
The non-response rate for 2006 was 1.8% which is the same rate as that for 2001. Unlike some other census variables the non-response rate is not affected by persons imputed into dwellings that did not return a Census form, as Method of Travel to Work (MTWP) is only applicable for persons with a labour force status of employed.
When using this data it is important to understand that MTWP is based on a different reference period (Census day) to other Census data relating to employment (last week). This may help explain why, for a small proportion of records, method of travel to work may appear inconsistent with place of work information.
In a small proportion of cases (testing has indicated that this is less than 2%), respondents provided more than three responses or an invalid combination of responses. Responses are normally accepted in the order they appear on the form and extra responses are rejected. However, for MTWP, in cases where the combination of responses contained "Did not go to work", "Worked at home" and "Walked only" then these unique responses override any others. If more than one of these unique responses is in the same combination then a single response is selected in the order they appear above.
2001 Method of transport to work data contains a small number of data errors pertaining to travel by tram, and to a lesser extent to travel by truck, which were not discovered until after the release of the census results.
During the 2001 census testing cycle, an electronic lookup table containing valid MTWP response combinations was constructed, as a reference for the main edits program. Unfortunately, a late change to the processing order of the options presented on the forms resulted in some valid response combinations not being added to the lookup table. During processing, where two or more responses were marked, with either Tram or Truck as the first mode encountered, the results were not processed in that order, and were therefore not recognised as a valid combination on the lookup table. MTWP was set to Not Stated for these records.
where both Tram (the 4th response option on the form) and Taxi (5th response option) were marked, Taxi was processed as Response 1, and Tram as Response 2. The resultant combination 'Taxi + Tram' was not a valid entry in the lookup table, so was coded to MTWP Not Stated.
Across Australia, 9,251 people who travelled by Tram plus another mode were affected: 8,748 (94.6%) of these lived in the Melbourne Statistical Division.
There are no similar issues with 2006 Census data, however the issues with the 2001 data may affect comparisons between 2001 and 2006.
The ABS aims to produce high quality data from the Census. To achieve this, extensive effort is put into Census form design, collection procedures, and processing procedures.
There are four principal sources of error in Census data: respondent error, processing error, partial response and undercount. Quality management of the Census program aims to reduce error as much as possible, and to provide a measure of the remaining error to data users, to allow them to use the data in an informed way.
When completing their Census form, some people do not answer all the questions which apply to them. In these instances, a 'not stated' code is allocated during processing, with the exception of non-response to age, sex, marital status and place of usual residence. These variables are needed for population estimates, so they are imputed using other information on the Census form, as well as information from the previous Census.
The processing of information from Census forms is now mostly automated, using scanning, Intelligent Character Recognition and other automatic processes. Quality assurance procedures are used during Census processing to ensure processing errors are kept at an acceptable level. Sample checking is undertaken during coding operations, and corrections are made where necessary.
The Census form may be completed by one household member on behalf of others. Incorrect answers can be introduced to the Census form if the respondent does not understand the question or does not know the correct information about other household members. Many of these errors remain in the final data.
More detailed information on data quality is available in the 2006 Census Dictionary (cat. no. 2901.0), in the section titled Managing Census Quality.