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Accuracy and reliability

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Agnes Tassy
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Cultural Habits Survey

The cultural habits survey is based on approx. 3,000 completed interviews per. quarter, which is a relatively robust sample that helps reduce the uncertainty of results. The uncertainty is further reduced by using a mixed data collection method and repeated inquiries to the respondents. The results of the survey can be compared with other statistics in several areas. These comparisons show a good coincidence.

Overall accuracy

An important source of uncertainty in this study is the sample uncertainty. Measured by key indicators, this source of uncertainty is less than one percent. There are answers from respectively 55 and 48 percent of those surveyed in the first two quarters of the survey, which is a further source of uncertainty for the study. It is also the case that certain types of groups more often do not respond and it affects the representativeness of the study. However, this is largely addressed through the enumeration and use of register-based assistance information. Although the assistance information tackles a lot of bias, it cannot be ruled out that there is systematic bias in the cultural consumption study. However, this will only affect the level and not the development.

Other sources of uncertainty, for example memory errors, are also relevant to the cultural consumption study. In order to reduce memory errors, respondents are questioned in recent weeks or in the past three months. This reduces the risks of memory errors in comparison with previous studies, which measured cultural consumption over a longer period, e.g. in the last year.

The precision of the cultural consumption survey can also be assessed by comparing selected results from the survey with relevant data from other statistics.

For example, the study estimates that six out of ten people stream music. The same proportion is calculated in the study 'IT use in the population 2018', where it is estimated that 63 per cent of the Danes between the ages of 16 and 89 stream music. The cultural consumption survey also shows that approx. 52 per cent of the Danes see movies or series via paid streaming services e.g. Netflix. The proportion is estimated at 50 per cent in the statistics "IT use in the population 2018".

27 per cent of the Danes state in the cultural consumption study that they use running watch, pedometer etc. when exercising. This proportion can be compared with the latest version of the statistics "Electronics in the home 2018". Here, it is estimated that 30 per cent of families own activity clock. Finally, the statistics on electronics in the home show that 9 per cent of the families are in possession of e-book readers. A share that is in line with the Cultural consumption survey's estimation for the proportion of Danes reading literature via e-book reader (10 per cent).

Based on the above-mentioned comparisons, the accuracy of the Cultural consumptionstudy seems to be high for the relevant indicators.

Sampling error

Sample uncertainty is measured by standard error, which expresses the uncertainty on the average of the estimates. The sample uncertainty is affected by the size of the sample. The uncertainty is reduced by half, for example, substantially if you quadruple your interview basis. The more responses the survey results are based on, the more secure the numbers are.

The standard error for selected indicators is less than one percent in the first two data collection rounds of the Cultural consumption survey.

Non-sampling error

To cover the population in the best way possible , the sample for the study is drawn very close to the data collection start time.

It is a comprehensive questionnaire the respondents are faced with. This can cause fatigue in the filling and thus uncertainty in relation to the extent of cultural consumption they provide. It can be difficult for the respondents to remember what they have done, e.g. three months back in time, which can also give uncertainty in relation to the extent of cultural consumption that is measured. Some forms of cultural consumption are perceived by many as "better" than others - for example, it is often perceived as better to read books or go to a museum than to watch movies or series on Netflix. This can lead to the respondent wishing to give a better impression of themselves and therefore they will therefore idealize the truth, which is also a source of uncertainty for the extent of cultural consumption measured. Because the scope of these sources of security is difficult to measure, but since the questionnaire does not contain particularly sensitive questions or issues of complicated technical nature, it is believed that the extent of this type of error is very limited. An additional source of insecurity is obsolete information about the background information requested e.g. education, family type or socioeconomic status. Background variables are therefore drawn from Statistics Denmark's various statistical registers as close to the survey reference period as possible. However, there is always a subset of the sample, where the register information is no longer true at the time of data collection, for example due to recent changes in educational level or family composition. There are responses from 54 percent in first quarter 2019, 55 percent in second quarter and 48 percent in third quarter. Of the 45 per cent who responded in the second quarter, 3 per cent of the answers have such major shortcomings are that they have not been included in the study. Several measures have been taken to reduce the discontinuation of the study. Thus, information is collected both via a web form and via telephone

The COVID-19 situation is not expected to have an influence on the quality of the results for the 2nd quarter 2020. The data collection process was the same as in the previous quarters, no deviations.

Quality management

Statistics Denmark follows the recommendations on organisation and management of quality given in the Code of Practice for European Statistics (CoP) and the implementation guidelines given in the Quality Assurance Framework of the European Statistical System (QAF). A Working Group on Quality and a central quality assurance function have been established to continuously carry through control of products and processes.

Quality assurance

Statistics Denmark follows the principles in the Code of Practice for European Statistics (CoP) and uses the Quality Assurance Framework of the European Statistical System (QAF) for the implementation of the principles. This involves continuous decentralized and central control of products and processes based on documentation following international standards. The central quality assurance function reports to the Working Group on Quality. Reports include suggestions for improvement that are assessed, decided and subsequently implemented.

Quality assessment

The study is considered relevant as the questionnaire has been developed in collaboration with users. Reliability is ensured by having openness about metadata, such as response rate, dropout, uncertainty calculations and any revisions and detailed information on processing data. The statistics can only be compared to a lesser extent with previous cultural consumption studies. This is due, firstly, to a method change where the reference period has changed from one year to the last three months. Secondly, the questionnaire is revised in relation to previous questionnaires to more accurately reflect today's cultural consumption, which is often digital. Thus, the statistics are more up to date and published more frequently (every quarter). Finally, it should be noted that in the period 2018-2020 minor adjustments are expected in the questionnaire in order to ensure a more optimal coverage of the target population's cultural and media consumption as well as leisure activities.

Data revision - policy

Statistics Denmark revises published figures in accordance with the Revision Policy for Statistics Denmark. The common procedures and principles of the Revision Policy are for some statistics supplemented by a specific revision practice.

Data revision practice

There are only calculated final figures.