Religious affiliation (information about this variable and its quality)

Priority level

Priority level 3

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

Religious affiliation is a priority 3 variable. Priority 3 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 in terms of quality, time and resources across all phases of a census.

The census priority rating for this variable remains the same as 2013.

Quality Management Strategy and the Information by variable for religious affiliation (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

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

How this data is classified

Religious Affiliation 1999V2.0.0

Religious affiliation is a hierarchical classification with three levels. Level 1 has 10 categories, level 2 contains 51 categories and level 3 contains 167 categories. Level 1 is shown below:

0 No Religion

1 Buddhism

2 Christian

3 Hinduism

4 Islam

5 Judaism

6 Māori religions, beliefs and philosophies

7 Spiritualism and new age religions

8 Other religions, beliefs and philosophies

9 Residual categories (includes object to answering)

Respondents could write multiple answers to the religion question. If more than one religion was reported, each response up to a maximum of four responses was counted. For respondents who provided more than four religions, more detailed responses are prioritised over vague or residual responses. As this is a multiple response variable, the total number of responses in a table is greater than the total number of people stated.

There have been some changes to the lowest level of the classification since 2013. Some religions have been added such as:

• Mahayana Buddhism
• Arise Church
• Shi’a
• Sunni
• Pagan
• Jedi
• Church of the Flying Spaghetti Monster.

Some religions have moved or merged categories. For example:

• Nazarene moved from other Christian to Methodist religions
• Plymouth Brethren and Exclusive Brethren merged into one category of Plymouth or Exclusive Brethren.

Aria has the full list of changes to the classification.

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

Question format

Religious affiliation is collected on the individual form (question 16 on the paper form).

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

There has been a change to the question format since the 2013 census. In 2013, tick boxes were provided for no religion, Christian, Buddhist, Hindu, Muslim, Jewish, Other religion, and Object to Answering. An inset box provided tick boxes for further detail on Christian denominations. The tick boxes used in the 2013 census have been replaced by a text box enabling respondents to state their religious affiliation(s) at the level of detail they need.

There were no differences between the wording or question format in the online and paper versions of this question. However, there were differences between the modes of collection (paper and online form).

On the online individual form:

• as-you-type functionality helped respondents provide valid, detailed responses.

On the paper individual forms:

• responses outside the valid range were possible.

How this data is used

Outside Stats NZ

• By researchers and religious organisations to trace the changes in values and belief systems in New Zealand society.
• To assess the need for various types of religion-related or religion-sponsored services, including those of churches, mosques, temples, and religious schools; and for the care of the aged and other disadvantaged groups.
• By churches, mosques, temples, and religious groups to assess their level of support within the wider community.
• As an explanatory variable for studies on subjects such as marriage formation and dissolution, educational attainment, and income.
• By Māori, Pacific peoples, and other ethnic groups for whom this information is an important aspect of their culture.

Within Stats NZ

• As part of measuring culture and identity along with the Ethnicity, Birthplace, Years since arrival in New Zealand, and Languages spoken variables.
• As part of information tables about people aged 65 and over.

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 religious affiliation data for a person in the subject population.

Please note that when examining religious affiliation data for specific population groups within the subject population, the percentage that is from 2013 Census data and statistical imputation may differ from that for the overall subject population.

Missing and residual responses

‘No information’ in the data sources table above is the percentage of the subject population coded to ‘not stated’. In 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 and imputation described above.

Percentage of ‘not stated’ for the census usually resident population:

• 2018: 0.0 percent
• 2013: 7.1 percent
• 2006: 6.2 percent.

In 2018, there were no residual responses remaining in the data due to the use of alternative data sources to replace them. In output for previous censuses, responses that could not be classified or did not provide the type of information asked for were grouped with ‘not stated’ and classified as ‘not elsewhere included’.

Percentage of ‘not elsewhere included’ for the census usually resident population:

• 2018: 0.0 percent
• 2013: 8.2 percent
• 2006: 7.3 percent.

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.

2013 Census data and within household imputation were mostly comparable to 2018 Census responses, while responses sourced through donor responses were moderately comparable to 2018 Census responses. The proportions of the alternative data sources along with the ‘no information’ rate of zero contributed to the score of 0.95, 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

Religious affiliation 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, incorporation of other sources of data, or a change in how the variable has been collected.

Data was checked to level three of the classification at the regional council level and compared with trends from the 2013 and 2006 data. The change to the collection of data (replacing tick box responses with write-in responses) resulted in more detailed responses and higher counts for some categories at lower levels of the classification.

Data quality: High quality

The data quality checks for religious affiliation included edits for consistency within the dataset and cross-tabulations to the national and regional council level of geography.

Religious affiliation 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 implementation of as-you-type functionality for the online forms helped ensure valid responses were provided.

Recommendations for use and further information

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

However, when using this data you should be aware that:

• although there are some changes to the collection and classification of religious affiliation, including the ability for respondents to provide more detail on their religious affiliation, real-world change such as increasing ethnic and religious diversity in New Zealand is the key driver in changes in religious affiliation from previous censuses
• the category of Māori Religions, Beliefs and Philosophies has the lowest rate of responses from census forms and the highest rate of alternative data sources. This is due to the overall low response rate for Māori in the 2018 Census.
• a proportion of responses have been sourced from 2013 Census data. Although people may have changed their religion(s) since the 2013 Census, this is still considered higher quality data than statistical imputation, or a residual or missing response.

Comparisons with other data sources

Census is the only comprehensive source of information about this variable

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