Total personal income (information about this variable and its quality)

Priority level

Priority level 2

We assign a priority level to all census variables: Priority 1, 2, or 3 (with 1 being highest and 3 being the lowest priority).

Total personal income is a priority 2 variable. Priority 2 variables cover key subject populations that are important for policy development, evaluation, or monitoring. These variables are given second priority in terms of quality, time, and resources across all phases of a census.

The census priority level for total personal income remains the same as 2013.

Quality Management Strategy and the Information by variable for total income (2013) have more information on the priority rating.

Overall quality rating for 2018 Census

High quality

Data quality processes section below has more detail on the rating for this variable.

The External Data Quality Panel has provided an independent assessment of the quality of this variable and has rated it as high quality. 2018 Census External Data Quality Panel: Assessment of Variables has more information.

Subject population

Census usually resident population aged 15 years and over.

‘Subject population’ means the people, families, households, or dwellings to whom the variable applies.

How this data is classified

Census Income bands 2018 V1.0.0

Total personal income is a flat classification with income band categories from zero to $150,001 or more, and a category for loss.

11 Loss

12 Zero income

13 $1-$5,000

14 $5,001-$10,000

15 $10,001-$15,000

16 $15,001-$20,000

17 $20,001-$25,000

18 $25,001-$30,000

19 $30,001-$35,000

20 $35,001-$40,000

21 $40,001-$50,000

22 $50,001-$60,000

23 $60,001-$70,000

24 $70,001-$100,000

25 $100,001-$150,000

26 $150,001 or more

99 Not stated

The classification of total personal income in the 2018 Census is consistent with that of the 2013 Census but not the 2006 Census. In 2013:

• the 2006 income bracket $50,001-$70,000 was split
• two higher income bands were included: $100,001-$150,000 and $150,001 or more.

Total personal income can also be grouped for output at smaller geographical areas and for cross-tabulation with other census variables. For example, it can be grouped into the following broader bands:

Census grouped personal income V2.0.0

1 $5000 or less

2 $5,001-$10,000

3 $10,001-$20,000

4 $20,001-$30,000

5 $30,001-$50,000

6 $50,001-$70,000

7 $70,001 or more

9 Not stated

The Standards and Classifications page provides background information on classifications and standards.

Question format

Total personal income is collected on the individual form (question 35 on the paper form).

Stats NZ Store House has samples for both the individual and dwelling paper forms.

There were no differences between the wording or question format in the online and paper versions of this question.

However, there were differences in the way a person could respond:

On the online individual form:

• respondents could only tick one answer.

On the paper individual form:

• multi-responses were possible.

Data from the online forms may therefore be of higher overall quality than data from paper forms. However, processing checks and edits were in place to improve quality of the paper forms. Data Quality Processes has more information.

Related variables

Total personal income can be combined with other information from the same family or household to provide:

• combined parental income for couples with child(ren)
• grouped combined parental income for couples with child(ren)
• total family income
• grouped total family income
• total household income
• grouped total household income
• total extended family income
• grouped total extended family income.

Family and household income derivations are not included in output of the 2018 Census at this stage due to data quality issues with family and household data.

How this data is used

Outside Stats NZ

• to formulate social and economic policy and monitoring programmes
• to develop the New Zealand Deprivation Index
• for research and planning by central and local government agencies.

Within Stats NZ

• to stratify the sample for ongoing surveys such as the Household Economic Survey (HES) and Household Labour Force Survey (HLFS).

2018 data sources

We used alternative data sources for missing census responses and responses that could not be classified or did not provide the type of information asked for. Where possible, we used responses from the 2013 Census, administrative data from the Integrated Data Infrastructure (IDI), or imputation.

The table below shows the breakdown of the various data sources used for this variable.

The ‘no information’ percentage is where we were not able to source total personal income data for a person in the subject population.

Administrative data sources

Data from the following administrative source was used:

For total personal income, we derived data from Inland Revenue which provides income information from the following registers:

1. The most recent filing of:

• Personal tax summary
• Individual income return (IR3).

2. Tax year summary derived from the following forms:

• Employer monthly Schedule (EMS)
• Individual income return (IR3)
• Company shareholders details (IR4S)
• IR20.

Inland Revenue collects income as actual dollar values but these are output into the income bands classification as described in ‘How this data is classified.’

Please note that when examining total personal income data for specific population groups within the subject population, the percentage which is from 2013 Census data, administrative data, and imputation may differ from that for the overall subject population.

It is important to note the following caveat relating to the use of admin data for the total personal income variable:

• some people may have only partial information for the 2018 tax year sourced from admin data. 2017 tax year data was sourced from admin data only when we did not have any information for the 2018 tax year.

For further information on the process of deriving income data from the IRD for Census purposes, please refer to Comparing income information from census and administrative sources

Missing and residual responses

‘No information’ in the data sources table is the percentage of the subject population coded to ‘not stated’. In recent previous censuses, non-response was the percentage of the subject population coded to ‘not stated’. In 2018, the percentage of ‘not stated’ is zero due to the use of the additional data sources described above.

Percentage of ‘not stated’ for the census usually resident population aged 15 years and over:

• 2018: 0.0 percent
• 2013: 9.7 percent
• 2006: 10.2 percent.

As with recent previous censuses, there are no other residual categories in the total personal income data.

2013 Census data user guide provides more information about non-response in the 2013 Census.

Data quality processes

Overall quality rating: High quality

Data was evaluated to assess whether it meets quality standards and is suitable for use.

Three quality metrics contributed to the overall quality rating:

• data sources and coverage
• consistency and coherence
• data quality.

The lowest rated metric determines the overall quality rating.

Data quality assurance for 2018 Census provides more information on the quality rating scale.

Data sources and coverage: High quality

We have assessed the quality of all the data sources that contribute to the output for the variable. To calculate a data sources and coverage quality score for a variable, each data source is rated and multiplied by the proportion it contributes to the total output.

The rating for a valid census response is defined as 1.00. Ratings for other sources are the best estimates available of their quality relative to a census response. Each source that contributes to the output for that variable is then multiplied by the proportion it contributes to the total output. The total score then determines the metric rating according to the following range:

• 98–100 = very high
• 95–<98 = high
• 90–<95 = moderate
• 75–<90 = poor
• <75 = very poor.

Admin data was mostly comparable to 2018 census responses, while data sourced through statistical imputation was moderately comparable to census forms. The high proportion of data from received forms and admin sources in comparison to the low proportion sourced from statistical imputation contributed to the score of 0.96, determining the high quality rating.

Data sources, editing, and imputation in the 2018 Census has more information on the Canadian census edit and imputation system (CANCEIS) that was used to derive donor responses.

Consistency and coherence: High quality

Total personal income data is consistent with expectations across nearly all consistency checks, with some minor variation from expectations or benchmarks that makes sense due to real-world change or incorporation of other sources of data. Personal income levels are expected to change over time.

• there is a higher proportion of people in the total personal income bands between $15,001-$25,000 than in the 2013 Census. This is in line with expectations, given the higher proportion of people receiving superannuation.

As well as the real-world change, the use of admin data may have increased the counts for the lower incomes bracket, contributing to a slightly lower than expected median total personal income:

• census records, including income data, was available for people who may have previously been missed from the census, including those in the lower income bands.
• missing income responses from paper forms have been replaced with admin data or statistical imputation in 2018. In 2013, these were coded to ‘not stated’.
• some sources of income that may be supplementary to the income we collected, such as investments, were not always available in the admin data.

Data quality: High quality

Total personal income data has only minor data quality issues. The quality of coding and responses within classification categories is high. Any impact of other data sources used is minor. Any issues with the variable appear in a low number of cases (typically in the low hundreds).

The data quality process for total personal income included cross-variable checks for consistency within the dataset, including with sources of personal income. For example, missing responses to total income were assigned to ‘zero income’ if a respondent had selected ‘no sources of income’ on paper forms.

Recommendations for use and further information

We recommend that the use of the data can be similar to that produced in 2013.

When using this data you should be aware that:

• data has been assessed to be consistent at the regional council level of geography. Some variation is possible at geographies below this level.

Care must also be taken when cross-tabulating census total personal income with sources of personal income:

• people may obtain income from more than one source
• the time reference periods are different between the two variables. Total personal income relates to 12 months ending on 31 March 2018, in line with the tax year whilst sources of income collects information for the 12 months ending 6 March 2018 (census night).

Comparisons with other data sources

Although there are surveys and sources other than the census that collect total personal income data, data users are advised to familiarise themselves with the strengths and limitations of the sources before use.

The Household Labour Force Survey (HLFS) provides more regular information on income (on an annual basis), but depending on the type of analysis being undertaken, it may be more appropriate to use census data. Data users are advised to familiarise themselves with the strengths and limitations of the sources before use:

• census aims to account for the total personal income of all usual residents aged 15 and over, while HLFS is only based upon a sample of the population
• census includes more sources of income than the HLFS, which only collects wages and salaries, self-employment and government transfers income
• census collects information on income earnt to March of the census year whereas the HLFS collects weekly income data during the June quarter, and a person’s income could change over a year.

Contact our Information Centre for further information about using this variable