Main means of travel to work 2013 Census (information about this variable and its quality)

##Where the data comes from

Question 41 on the individual form.

##How this data is classified 01 Worked at home

02 Did not go to work today

03 Drove a private car, truck or van

04 Drove a company car, truck or van

05 Passenger in a car, truck, van or company bus

06 Public bus

07 Train

08 Motor cycle or power cycle

09 Bicycle

10 Walked or jogged

15 Other

77 Response unidentifiable

99 Not stated

The 'Other' category includes taxi, ferry, helicopter, aeroplane.

For further information about this classification, refer to the:

• 2013 Census data dictionary
• Statistical standard for main means of travel to work.

For background information on classifications and standards, refer to the Classifications and related statistical standards page.

##Subject population

The subject population for this variable is the employed census usually resident population aged 15 years and over.

The subject population is the people, families, households, or dwellings to whom the variable applies.

##Non-response and data that could not be classified

Non-response 'Non-response' is when an individual gives no response at all to a census question that was relevant to them. The non-response rate is the percentage of the subject population that was coded to ‘Not stated’.

• Non-response rate for 2013: 2.5 percent.
• Non-response rate for 2006: 3.7 percent.
• Non-response rate for 2001: 3.5 percent.

Not elsewhere included

Non-response and responses that could not be classified or did not provide the type of information asked for are usually grouped together and called 'Not elsewhere included'.

• 3.7 percent of the subject population was coded to 'Not elsewhere included' in 2013, compared with 5.3 percent in 2006. This category was not present in 2001.

For more information on non-response and substitute records, refer to the 2013 Census data user guide.

##How this data is used

Data from this variable is used:

• in conjunction with workplace address to measure traffic flows of the employed population
• extensively by transport planners to plan and manage transport, particularly in large cities like Auckland and Wellington where congestion is a problem
• to gauge the growing number of people working from home
• to apportion urban transport levies between local authorities
• by Statistics NZ to produce analytical reports on trends in travel to work patterns, such as Commuting Patterns in New Zealand: 1996–2006.

##Data quality processes All census data was checked thoroughly during processing and evaluation, to ensure that it met quality standards and is suitable for use. These quality checks included edits.

All data must meet minimum quality standards to make it suitable for use.

Quality level A quality level is assigned to all census variables: foremost, defining, or supplementary.

Main means of travel to work is a supplementary variable. Supplementary variables do not fit in directly with the main purpose of a census, but are still important to certain groups. These variables are given third priority in terms of effort and resources.

Mode of collection impacts – online form compared with paper form The online forms had built-in editing functionality that directed respondents to the appropriate questions and ensured that their responses were valid. As a result of this, data from online forms may be of higher overall quality than data from paper forms. The significance of this will depend on the particular type of analysis being done. There will always be a mode effect but this cannot be measured. Statistics NZ design and test to minimise the effects of mode for all questions.

There were differences between how the forms were completed online and on paper for this variable:

• The online form allowed only one response to be selected for the main means of travel to work question. If a further response was selected, the response given previously disappeared. Multiple responses to this question were possible when forms were completed on paper.
• On the online form, only people who answered that they were in employment in question 32 and were 15 years of age or older, and gave a New Zealand address in question 5 were able to respond to the main means of travel to work question. When forms were completed on paper, it was possible for people who were not working, younger than 15 years, or overseas visitors to answer this question.

##Quality assessment of data and data quality issues for this variable Overall quality assessment High: fit for use – with minor data quality issues only. 2013 Census variable quality rating scale gives more detail.

Issues to note

• Non-response rate for 2013: 2.5 percent.
• Data conforms to expectations and non-response is lower than 2006.
• Data must be extracted with the subject population applied – New Zealand resident adults employed full or part time – otherwise inconsistent results can be produced such as unemployed people having a travel to work journey. Note that inconsistencies can occur when comparing 'Worked at home' counts from travel to work variable with 'Work at home' for workplace address indicator variable, due to differences in the reference period. For more information on non-response and substitute records, refer to the 2013 Census data user guide.

##Comparing this data with previous census data This data is fully comparable with the 2006 Census data. Changes in the data over this time period can be interpreted as real changes because there have been no changes in the way the data has been collected, defined, and classified.

This data is highly comparable with the 2001 Census data. Changes in the data over this time period can generally be interpreted as real changes. There may be a small component of change over time that is due to minor changes in the collection, definition, or classification of the data.

Since 2001 there has been a minor change in the question and a change in the treatment of multiple responses.

In 2001 the motorbike category was worded 'Motorbike or power cycle', but for 2006 and 2013 this category was just 'Motorbike', and power cycles were not mentioned. In 2001 the first box marked was coded when a multiple response was given, whereas in 2006 and 2013 true multiple responses were coded to 'Response unidentifiable'. These changes have had little effect on the data because power cycles are a rare form of transport and the number of multiple responses to this question is very low.

##Comparing this data with data from other sources No alternative data source is available from Statistics NZ.

##Further information about this data All percentages in census publications have been calculated using 'Total stated' as the denominator.

When using this data, be aware that:

• Inconsistencies can occur when comparing 'Worked at home' counts from the main means of travel to work variable with 'Work at home' counts from the workplace address indicator variable. This is due to differences in the reference period. Workplace address data relates to the seven-day period ending on the Sunday before census day, whereas travel to work data relates to census day.

Contact our Information Centre for further information about using this variable.