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Secondary data

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Points to consider as you decide if information collected elsewhere is useful for your evaluation.

What is secondary data?

Secondary data is information that already exists, collected by other people or organisations for a different purpose.

It is usually readily available, although special permission may sometimes be needed to access it.

It contrasts with data that you collect yourself through direct contact with respondents, for example, through interviews or a questionnaire.

Secondary data may be provided by previous evaluations of a project or programme, or a mid-term report, or it may be routine data collected by organisations.

Secondary sources can provide both quantitative and qualitative data. Secondary data can be raw statistics or more unusually raw qualitative source data such as interview transcripts. More usually it is data that is already contained in articles, publications, reports and other documents.

It will be helpful to consider how far the secondary data meets a number of key criteria:

  • availability
  • relevance
  • appropriateness
  • reliability
  • replicability.

Why use secondary data?

One of the main reasons for collecting secondary data is to avoid duplicating work that has already been done. If you can use secondary data sources, you may be able to save both time and expense.

There are other reasons for reviewing or collecting secondary data.

  • It will show the gaps in existing information and the quality of evidence already available.
  • It can provide a context in which to place your analysis of the primary data that you are collecting.
  • It can give you a greater understanding and insight into the problems, issues and practice related to the field in which you are evaluating.
  • It can help to suggest evaluation questions.
  • It can provide a basis for comparison for the data that you are collecting.

Using secondary sources

National statistics

You can freely access national and local statistics through government websites, such as and

The Office for National Statistics ( is the largest independent source of national statistics.

There are also a number of sites where you can get more specific data on different topics. 

Domestic violence

Crime You can also find data about reported incidents in a specific locality, for example, at

Refugees and immigration

Literature review

A literature review is a summary of relevant literature on a topic, or of research findings which relate to the project or programme being carried out.

If you want to summarise all past evaluation findings in a particular field, your review may need to be highly structured or systematic.

You might also contact similar programmes which have not yet published findings to learn about outcomes and best practice.

If you have the opportunity to work with other projects in the context of a larger programme, you may be able to review their data or evaluation findings.

Using existing survey data

If previous surveys have been carried out with your participant group, either for an earlier evaluation or for internal purposes, this may give you useful background or baseline information.

Document review

Many evaluations will include some element of a review of existing:

  • organisational documents
  • client records
  • other print or electronic records. 

You may wish to review:

  • formal reports
  • minutes of meetings
  • media reports.

You will be analysing them to extract themes related to the evaluation, to make a detailed analysis, or to extract specific content.

If you are doing a structured quantitative or qualitative analysis, it will be important to document the criteria you use to rate and analyse material.

Media analysis

A media monitoring service can be used to cover content and editorial opinion. This is particularly useful to evaluate the effectiveness of campaigns through the dissemination of key messages in print, broadcast online and social media.

Online desk research

Online desk research allows you to monitor for take up of resources, use of new approaches and practice, or the dissemination of key messages. This can be done through targeted searches of specific sources or through keyword searches. This may take you into researching governmental, educational, and voluntary sector websites, publications, strategies and guidance.


There are a number of challenges to consider when using secondary data.

Quality and accuracy

Your  use of the data and its validity will be highly dependent on the quality of the secondary sources used. 

Fit of data

There are a number of factors which may affect how appropriate the data is for your evaluation.

  1. Information may not quite fit the same frame or boundaries as your primary data collection. For example, the sampling may differ in important respects.
  2. Some issues, criteria or indicators may be addressed but not others.
  3. Concepts used may not be the same.
  4. Categories used may be different. Questions may be defined differently. For example, age or ethnicity under which data was collected may be different.
  5. Units of measurement may be different.

Gaps in data

Data may be available for some geographical areas and not others, or for certain time periods only

Currency of data

The data may be outdated.

Top tips

There are several checks that will help to make sure that your secondary data contributes to the collection of credible evidence.

  • Check that you have access to all relevant and available data, such as organisational records, so that you are not presenting a partial view.
  • Verify the dependability and reputation of the data source. Find out if their results are generally held to be valid.
  • Ask what quantitative and qualitative methods were used to collect the data.
  • Check the methods that were used to assure the quality of the data collection.
  • For surveys, try to obtain access to the questionnaire itself.

Find out the sample size and the sampling frame, and how representative the sample was. 
Check how the analysis was carried out. 
Check if the findings presented were consistent with the questions used.

Page last edited Dec 16, 2016

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