Step-by-step guide to using the ONS Longitudinal Study

1. Formulate your research question
2. Read the 'Is the LS for me?' page

If you haven't already read the What is the LS? (2) page, you should do so – it will tell you more about the type of data that the LS contains, and whether it will be useful for your study. If the LS is not for you, we might be able to suggest alternative sources of data that will be more suitable for your study.

You should also review existing work on the subject that has been done using LS data. You can find out more by looking at current and past projects as well as at our publications list.

3. Study our online training

We have developed ten online training modules to cover the use of the LS in a range of research areas. These can be accessed from our Online training page. The areas currently covered are:

  • Designing a study population
  • Analysing LS data
  • LS outputs
  • Socio-economic data
  • Ethnicity
  • Geography
  • Households and Families
  • Events (inc births, deaths, cancer registrations and widowhoods)
  • Fertility
  • Mortality
  • These modules provide a wealth of information on the variables available, suitable research designs and also give indicators of sample sizes. You can also get further ideas and inspiration by looking at our downloadable tables.

    If you have any doubts about the suitability of the LS for your research contact us at, or by phoning 020 7299 4634.

    4. Contact CeLSIUS

    If you are an academic user (i.e. staff or student based in a Higher Education institution in the UK), and you think the LS might be suitable for your needs, contact the CeLSIUS Executive Officer, either by e-mailing, or by phoning 020 7299 4634.

    The Executive Officer will discuss your research question and your timescale, and pass your request on to our technical staff as appropriate. They will guide you through the subsequent processes to make sure you get the data that is appropriate to your research question.

    If you are a non-academic user, please contact the LS Unit at the Office for National Statistics (ONS) directly.

    5. About the application forms

    There are three forms to complete. At the present time we estimate that from submission of your application to CeLSIUS to full and final approval (which must be given before any data can be released) you should allow from 6 to 8 weeks.

    Form What is this form for?

    Customer Request Form (CRF) pages 1-2


    ONE form for each project:

    This is where you tell us more about yourself and your project.

    CRF Supplement Part B (access to the ONS LS)

    This is where you tell us in more detail about the data you wish to use. This section is usually completed in collaboration with your Research and Computing Support Officer.
    Data Access Agreement (DAA)

    ONE form for each project:

    Signed on behalf of the project by the lead researcher.

    Approved Researcher form (ARF) ONE form for each named person on the project:

    A requirement to establish the researcher as a 'fit and proper person' under the terms of the Statistics and Registration Act 2007.

    We strongly recommend that you complete and submit drafts of all forms at the same time as your main application form (CRF) as this can save unnecessary delays in the approval process.

    6. Tell us about yourself and your project: Customer Request Form (CRF)

    Pages 1 - 2 of the Customer Request form give us basic information for our records and a description of your research project. The application form is in Word. If you have Word 97 (or a later version), you can type your details straight into the form. It would be most convenient if you could also email the electronic copy to us.

    If you don't have a suitable version of Word, then you can download this PDF version (139K) instead, which you can print out and send to us by post.

    Once we receive the form, we will assign a CeLSIUS support officer to your project, who will contact you and help you proceed with completing Part B.

    7. Specify your data extract: CRF part B

    If you require one or two straightforward tables from the LS, either to establish whether the LS is likely to be useful, or to provide some background information, we can arrange this with a minimum of formality. To explore if this is a viable option for your research contact the CeSLIUS helpdesk.

    For most analyses, you will need to specify the dataset you want extracted, and how you want to receive the data. You should use the data dictionary to specify the variables that you want included– this can be changed later but it is helpful both to you and to those considering your project to draw up an initial list at this stage. The CeLSIUS support officer will assist you with this.

    Once the form is completed, we will submit it as an application to the LS Research Board (LSRB); at the same time, it will be submitted to the ONS Ethics and Confidentiality Committee. You can view the criteria for approval (PDF 10K) for the approval of applications (or the 10K HTML version). The LSRB then recommends the project for ratification to the ONS Microdata Release Panel.

    Once the LSRB has approved the project your Research and Computing Support Officer can start work on it but cannot release any data until the final approval is given by the ONS Microdata Release Panel.

    NOTE: The ONS Microdata Release Panel can only consider projects recommended by the LSRB once they also hold the completed and signed Data Access Agreement and have had confirmation that all named members of the research team have been given Approved Researcher Status.

    8. Complete the Approved Researcher form (ARF)

    The Approved Researcher form is a legal requirement under the Statistics and Registration Act 2007 and all named researchers will need to submit a form. The form is available as a Word document which can be completed electronically and emailed to CeLSIUS. But the Declaration MUST also be hand signed and hard copy of the forms returned to CeLSIUS.

    It is important to bear in mind that the Approved Researcher form is a legal document and must be able to justify your application in its own right; when completing it, provide specific information on your experience and research record (including technical experience of microdata analysis) and do not assume any prior knowledge on the part of the reader. You can see the criteria used to assess the ARF application in the guidance notes that preface the main form.

    9. Complete the Data Access Agreement

    The Data Access Agreement must be completed, signed and sent to CeLSIUS. If you have Word 97 (or a later version) you can type your details straight into the form. If you do not have a suitable version of Word you can download this PDF version.

    10. Attend a Safe Researcher Certification course

    While you are awaiting approval of your project, arrange to attend a half-day training course if possible. Courses are offered at intervals by MAUS (the ONS Microdata User Support Service) or by the Secure Data Service. Attendance at a course is a requirement for everyone using LS data, although you may be allowed to proceed with your research before attending one if there are no places currently available in your locality.

    11. Receive outputs from CeLSIUS

    The CeLSIUS officer assigned to your project will produce either aggregated data sets that you can analyse further at your own site, or outputs from analyses run at ONS. You may have visited the VML lab and run your analyses yourself.

    To maintain the security of the LS all preliminary outputs are encrypted before being sent out to users and the approved encryption software is Safeguard PrivateCrypto. If your institution does not have a Private Crypto licence CeLSIUS users can download a freeware version of the software from the Sophos Web site. Under certain circumstances CeLSIUS may be able to provide student researchers with an individual short term licence for the full software, please contact the CeLSIUS helpdesk to find out more.

    Individual-level datasets cannot be released. However, you can arrange to visit ONS to use individual-level data on site, but must book a place in advance. You can find out more about arranging this from your Support Officer as well as the training requirement for all researchers planning to use the LS.

    12. Seek Final Output clearance for results to be made public

    When you want to disseminate your LS results beyond your named Approved Researchers in your project team you must obtain final outputs clearance from the LS Research Board.

    The process for clearing final outputs reduces the risk of disclosure and ensures that the LS is properly described. Key criteria include:

    • Results aggregated to a minimum cell threshold. ONS asks that in results from which a count of individual persons could be calculated, that count is 10 or more. However, ONS will consider giving clearance to results which do not meet this criterion, if there is a scientific justification.
    • The LS is described correctly. Standard descriptions are available.
    • 'Source: ONS Longitudinal Study' added to tables and figures, where appropriate.
    • Results appreciate that the LS includes data for England and Wales only.

    Final outputs may be either working papers, reports, journal articles, presentations or abstracts, or simply a set of results which are destined to be worked up as any of these. Allow 5 working days for final outputs clearance although many outputs are cleared more quickly than this. Complete an LS outputs clearance form and send it with a copy of your work to us:

    Again, if you have MS Word 97 (or a later version), you can type your details straight into the Word form and email the electronic copy to us. There is no need to send a printed copy in this case. We will forward your application to the LS Research Board.

    Once your final output has been cleared for public release you may disseminate it a number of times without resubmitting it for clearance, as long as no new results are included. Your cleared final outputs are given a clearance number which you should cite in your publications.

    You are asked to acknowledge the support of CeLSIUS and ONS in your publications and include a disclaimer. We have a suggestion below:

    "The permission of the Office for National Statistics to use the Longitudinal Study is gratefully acknowledged, as is the help provided by staff of the Centre for Longitudinal Study Information & User Support (CeLSIUS). CeLSIUS is supported by the ESRC Census of Population Programme (Award Ref: RES-348-25-0004). The authors alone are responsible for the interpretation of the data."

    The following copyright statement should be featured along with the above acknowledgement:

    "Census output is Crown copyright and is reproduced with the permission of the Controller of HMSO and the Queen's Printer for Scotland".

    If you need to cite ethical approval for the ONS LS itself, you should refer to PIAG and NIGB.

    13. Notify CeLSIUS of publications arising

    You should also notify CeLSIUS when your paper is actually published or your presentation made. If you are a registered user of other Census data services (this is not necessary to be an LS user), the simplest method of recording publications may be to use the on-line notification form at (log into and look for 'Submit Outputs' under the 'Data Use' list on the left). Otherwise just e-mail us at

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    Last modified 7 February 2012