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Guide to experimental statistics - frequently asked questions

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Frequently asked questions about Office for National Statistics (ONS) statistics in development.

What are experimental statistics?

These are series of statistics that are in the testing phase and not yet fully developed.

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How should users interpret such series?

Users should be aware of the status and cautions of these series, which will vary for each statistic. The particular limitations of each series are explained in the accompanying information for each.

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Why is the number of experimental series increasing?

We regularly consult the users of our statistics during methodological reviews and the development stage of methodological changes. We recognise that making experimental series available during a development period assists in the quality assurance process and helps familiarise potential users with any changes. There have also been initiatives to increase the scope of our economic statistics, particularly within the service sector.

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When are statistics defined as experimental?

Defining what is experimental and non-experimental is largely a matter of statistical judgement, but typically experimental series are created when:

  • They are being produced part way through a well-defined development programme, whether these statistics are new or changed versions of existing statistics.

  • The statistics are new but still subject to testing in terms of their volatility and ability to meet customer needs.

  • The statistics do not meet the rigorous quality standards of National Statistics yet.

  • A rich variety of new measures is available from a new set of statistics, with components that have considerable immediate value to users. These users are aware of the statistics' theoretical quality and can use them before we have completed all operational testing. The testing is designed to fully validate the measures to the standard expected of National Statistics.

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What are the features of experimental statistics?

The experimental nature of such statistics may reflect:

  • New methods which are being tested and still subject to modification.

  • Partial coverage (for example, of industries) at that stage of the development programme.

  • Potential modification following user feedback about their usefulness and credibility compared to other available statistical sources.

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Why publish experimental statistics?

The reasons include:

  • Consultation: we would like to get informed feedback from potential users.

  • Acclimatisation: where the experimental series are alternative versions of the format of existing series, we may wish to help users become used to new presentations.

  • Use: experimental series can provide useful information for users as long as their nature is well-explained and understood.

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When do experimental statistics become non-experimental?

This will be a matter of statistical judgement, but will typically take into account factors such as:

  • when it is judged that statistical methods have settled down

  • when coverage reaches a good level

  • when user feedback indicates that these statistics are useful and credible

  • when the defined development phase has ended

  • when it is judged that the statistics meet the rigorous quality standards of National Statistics

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What is the procedure for removing experimental status?

Statistics classified as 'experimental statistics' are only made National Statistics following assessment by the UK Statistics Authority monitoring and assessment team.

For this to happen, there are 4 stages which must be followed:

  • stage 1: self-assessment by Business Area

  • stage 2: methodological review by our strategy and standards directorate methodologists and/or business area methodologist

  • stage 3: recommendation by the strategy and standards directorate, ONS director general's office and the statistical policy committee (SPC)

  • stage 4: assessment by the UK Statistics Authority

For Official Statistics, removing the experimental statistics label does not require UK Statistics Authority involvement.

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