Family food open data
Source: data.gov.uk (2018-05-16)

The National Food Survey was the predecessor of the Living Costs and Food Survey, and ran in some form from 1940 to 2000. Survey data from 1974 to 2000 is being provided as Open Data, in the form of tab-separated-value files in zip archive format, together with supporting background material in either tab-separated-value or Portable Document Format files.

More information on the Expenditure and Food Survey, the successor to the National Food Survey, and a link to archived National Food Survey reports for 1997 to 2000, can be found on the Family Food page on the GOV.UK site at https://www.gov.uk/government/collections/family-food-statistics.

If you require the datasets in a more accessible format, please contact familyfood@defra.gsi.gov.uk

Privacy Impact Assessment: releasing Family Food Survey 
data (1974 - 2000) as open data 
This assessment follows the template provided by the Information Commissioner’s 
Office (ICO) in their publication Conducting Privacy Impact Assessments: Code of 
Practice.  
 
 
Why are we undertaking a PIA? 
Our information flows 
Our consultation process 
Our key privacy, compliance and corporate risks 
Step five: Identify privacy solutions 
Step six: sign off 
Step seven: integrate PIA outcomes back into the project plan 
 
Why are we undertaking a PIA? 
Defra is planning to publish its archive of Family Food Survey data (1974 - 
2000) as open data. It wants to do this in a way that ensures the privacy of 
individuals who have been surveyed throughout that time period is protected 
and respected. Defra needs to take care that data published as open data (a) 
does not contain any personal data and (b) cannot be reidentified. This 
Privacy Impact Assessment forms part of Defra’s approach to managing 
risks associated with the publication of this archive.  
 
Defra has committed to publishing 8,000 datasets as open data by June 2016 
(#OpenDefra). While stimulating external and new uses of Defra data is a key goal 
of this project, it is also designed to kickstart cultural change across Defra and the 
transition to becoming a more collaborative, open organisation. 
 
Since the launch of #OpenDefra, Defra has begun publishing a significant array of 
environmental and observational data, predominantly through its arms-length bodies. 

It has developed an open data risk assessment (ODRA) process for working through 
risks associated with open data publication. To date, most data published could be 
described as ‘low risk’, with minimal issues relating to third party IP, personal data or 
commercial sensitivity.  
 
The publication of Defra’s archive of its National Food Survey data (1974 - 2000) as 
open data marks the first significant release of data that is derived from data 
provided by individuals.  Since 2000, the National Food Survey has been retitled as 
the ‘Family Food Survey’ and is still administered by Defra in partnership with ONS. 
‘Family Food Survey’ is used as an umbrella term for the data throughout this 
PIA.  
 
Since its origins, the Survey has captured a sample of households annually 
(approximately 7,000 from across the UK) and asks them to maintain a one week 
diary about what they eat and drink inside and outside the home. It’s a fascinating 
snapshot of how British eating habits at home have changed over the years. While 
this PIA relates only to the publication of its data archive from 1974 - 2000, Defra has 
been collecting data as part of the Family Food Survey since 1940. 
 
What are the goals from the publication of this data? 
 
The publication of Defra’s archive of Family Food Survey data has benefits for 
people and organisations both inside and outside the department. The richness of 
information it provides about eating and drinking habits throughout Britain over 
decades could be useful for: 
 
● analysing dietary and nutritional trends across Britain (for example, by 
combining it with nutritional data collected by the Food Standards Agency) 
● understanding the relationship between dietary trends and other social forces 
that shape UK communities (employment, industrialisation) 
● contributing to topical debates about obesity and sugar 
● informing new teaching aides and visualisations in schools - an exciting way 
for students to engage with British eating habits over time. 
 
Publishing its archive of Family Food Survey data also has benefits to Defra as a 
department: 
● it’s an engaging, easy to comprehend data source - a useful way to explore 
the possibilities of data, and how it reflects changes over time, with staff 
without specialist data backgrounds 
● it encourages new approaches to publishing data within existing Defra 
professions - as part of this process, the statistics profession in Defra will 
develop valuable experience drafting privacy impact assessments, assessing 
disclosure control risks, documenting disclosure control mechanisms, working 
with data users, and developing anonymization skills.  

 
The Family Food Survey has historically collected information not only about 
household eating and drinking habits across the UK, but also information about 
things like household numbers, ages of occupants, their gross income and type of 
employment. The need for a privacy impact assessment has been identified as part 
of the process preparing a version of the Family Food Survey data archive that is 
safe for release as open data. It will help Defra weigh the risks associated with the 
publication of this data in a way that balances the potential impacts of re-
identification of individuals in the survey, as well as the public benefit in making this 
data more accessible. The task was to produce a treated dataset which was both 
valuable in its content to end users and which safeguards respondents’ privacy to an 
acceptable level (both to Defra and them).  
 
 

Our information flows 
 
How has this data been collected? 
 
Contributions to the Family Food Survey have been collected per household, via 
paper-based surveys, since 1939. Copies of the survey are distributed to a number 
of households across the UK. On average, approximately 7,000 households from 
across the UK are surveyed each year. Households are sampled at random, and 
linking food diary entries to particular households over time is not possible.  
 
Some mechanisms around collection of the data have changed over the decades. In 
the 1970s, for example, surveys were typically supplied to the ‘housewife’ for 
completion, as person assumed in the household to have greatest understanding of 
what that household consumed over a two week period. 
 
By the late 1980’s, the designation ‘housewife’ was removed from the survey and it 
could be filled in by any household occupant. Food and drink consumed outside the 
home over a two week period were added as questions to the survey. 
 
This survey, like all household surveys, would have been accompanied by a 
commitment to respondent confidentiality. The exact wording is now lost, but we 
continue to give this the highest priority in preparing the data archive for open 
publication.  
 
Because this is a historic archive, information related to the original administration of 
the surveys has also been lost. The data Defra has access to may already have 
been cleansed of all direct identifiers, and had some disclosure control guidance 
applied. We do not know what other personal information may have been collected, 
and subsequently deleted, as part of data processing. We have commenced this 
PIA, and made changes to the data archive to reduce the risk of re-identification of 
individuals, based on the data that Defra has access to.  
 
What does this data look like? 
 
The ‘unprocessed’ data archive available within Defra does not include any direct 
identifiers like name of survey recipient, address or national insurance number. 
However, the data does include a number of variables that may make re-
identification of individuals and households in the data possible. The survey captures 
information including: 
 
● Age of household occupants 
● Gross income 
● Employment type  

● Whether any occupants were pregnant at the time of completion of the survey 
● Whether occupants had certain benefits 
● Sex 
 
The data archive is currently accessible via the UK Data Archive to users who 
register and agree to the terms & conditions of its End User Licence (EUL). Due to 
the age of the data, it’s unclear what disclosure control may have taken place prior to 
the uploading of Family Food Survey data to the UK Data Archive.  
 
Defra would like to publish a version of the data archive more widely as open data. 
It’s likely that some disclosure control will need to be undertaken prior to publication, 
to make the risk of re-identification of individuals contributing to the survey as remote 
as possible.  
Our consultation process 
Defra has set up an internal project group to manage the publication of Family Food 
Survey data as open data, spanning representatives from the Food & Farming 
statistics unit, the Defra Data Programme and Communications Directorate.  
 
The data archive doesn’t include any contact details or direct identifiers for 
households who were involved in the survey. As such, contacting survey 
respondents individually to seek their feedback on the project is impossible.  
 
As part of its preparation, the project group consulted: 
● inside Defra, with the Information Rights Management team to understand the 
relationship between the Data Protection Act and anonymization of data. 
● outside Defra, with the Office of National Statistics, to understand disclosure 
control guidance that is available and existing case studies of reuse of historic 
survey data, and with the UK Data Archive, to understand how the Family 
Food Survey data is managed via that platform.  
 
The project group set up an external group of trusted testers, to explore five years of 
unprocessed test data (1974 - 1978) and provide feedback on variables that they 
would find most useful, as well as share their thoughts on potential privacy risks 
associated with the project. Feedback from testers has helped to shape Defra’s own 
disclosure control testing.  
 
A draft of this privacy impact assessment was also shared with the external testers, 
as well as the information rights team in Defra, to provide feedback on how it could 
be improved. 
 
 

Our key privacy, compliance and corporate risks 
Risk One: Individuals can be re-identified using the Family Food Survey data 
 
The Information Commissioner’s Office has made clear that data protection law does 
not apply to data that has been anonymised; that is, changed in such a way that the 
data subject is longer identifiable. Defra is following ONS disclosure control guidance 
and the ICO Anonymization Code of Practice to reduce the likelihood as much as 
possible that this data could be re-identified. Nonetheless, we need to think through 
the impacts to individuals, and to Defra, were re-identification to occur.  
 
In some circumstances, even if identification of an individual from the data is 
possible, there may be no negative impact. An individual might recognise their own 
household from a diary entry. A neighbour or associate might make an educated 
guess about the identity of a household in the data. The food diary results do not 
divulge anything sensitive or unusual, and/or the recognition may occur privately. We 
can foresee instances where even if identification occurs, there’s no impact on 
individuals or government.  
 
There is still a risk that, even in the event no harm is experienced as a result of re-
identification, Defra may be found to have breached its obligations under the Data 
Protection Act. The ICO may launch an investigation into the circumstances which 
resulted in the re-identification of individuals. A finding by the ICO that Defra has 
negligently disclosed personal data about individuals could result in civil penalties 
and a fine of up to £500 000. The ICO has stated that ‘where there is evidence of 
re-identification taking place, with a risk of harm to individuals, the Information 
Commissioner will be likely to take regulatory action’ (20, Anonymization Code of 
Practice).   
 
Finally, there is a risk that a household or households is identified from the Family 
Food Survey data, with negative outcomes. A combination of certain unique 
household information is found to be that of a well-known household - e.g. a Minister, 
an MP, a celebrity, a public intellectual, athlete etc. The details of these food diaries 
form the basis of media stories revealing the eating habits of these public figures. 
These eating habits may not be unusual, or they may reveal details that are 
embarrassing to the figures. Alternatively, a food diary entry may be so unusual as to 
incentivise re-identification of the household surveyed, and - if achieved - result in a 
public focus on that household’s eating habits.  
 
 
 

Solution 
Defra has taken steps to ensure that the likelihood of identification is as remote as 
possible1. In order to assess the likelihood of identification, the team: 
 
● ran a range of count queries, looking for unique and low combinations of 
results in the data. Due to the sample nature of the survey, a large return of 
unique and low combinations did not necessarily mean the nature of the 
household information captured was unique (i.e. that only one household of 
four, with two children and two adults, from Bath, was captured by the survey 
does not mean that such a household is rare in Bath); 
● applied Skinner and Elliot’s data intruder simulation (DIS) method2 on a 
variety of combinations of variables to assess potential disclosure risk; and 
● spoke with external testers about their experiences of the data, and 
combinations of variables they considered to be unique. 
 
To reduce the risk of identification as much as possible, Defra has decided to: 
● Remove data records for households with more than 10 members 
● Where ages are recorded, band them into 7 age groups 
● Delete the gross income of head of household 
● Band the net family income into equivalised deciles (within the dataset, not 
national equivalised decile income points) 
● Merge the variables recording receipt of various benefits (Family Credit, 
Income Support, Housing Benefit, Working Family Tax Credit) into a single 
binary variable 
● Delete variables on religion (these were only recorded in Northern Ireland) 
● Not publish the ‘person’ table which recorded a number of details on each 
member of the household (age, sex occupation etc). A new person table will 
contain two binary variables identifying whether the household contains a) a 
pregnancy and b) any children under 3. 
 
As part of the data release, Defra will provide a mechanism for people to alert the 
team to any instances of identification or other privacy-related issues in the data. 
Text will be added to the data release pages with a contact email address 
(xxx@xxx.xx) asking data users to alert the team to any issues. If a 
privacy-related issue is raised and found to be valid, the data will be removed from 
data.gov.uk and any other locations until the issue is resolved.  
 
 
 
                                               
1 In a case between the Department of Health and the Information Commissioner [2011] 
EWHC 1430 (Admin), the court found that: ‘ the risk of identification must be greater 
than remote and reasonably likely for information to be classed as personal data’ .  
2 Skinner, C. J., & Elliot, M. J. (2002). A measure of disclosure risk for microdata. Journal of 
the Royal Statistical Society: series B (statistical methodology), 64(4), 855-867 

Risk Two: Regardless of any actual identification of individuals from the 
Family Food Survey data, the public perceives it to be a breach of their trust in 
government.  
There are increasing sensitivities around how government collects, accesses and 
uses our personal data. There may be a general perceived risk that Defra has not 
been managing its Family Food Survey data properly and securely (absent of any 
incidents, or based on identification of households). Participants in future surveys 
may, as part of the fallout from such a risk, refuse to participate in the Family Food 
Survey/other government surveys.  
 
Defra is heavily reliant on the continuance of surveys to collect data. As such, 
maintenance of the response rate into the future needs to be taken into account. 
Care must be taken to not only protect privacy, but be perceived as protecting 
privacy, in a way that also shows that the data is being used for the benefit of the 
nation, while respecting those who volunteered their time and data to DEFRA and its 
predecessors in the past. 
 
The ongoing administration of the Family Food Survey is the responsibility of the 
Defra statistics profession, who are bound by the UK Statistics Authority Code of 
Practice. The Code of Practice in its current form didn’t exist at the time this historic 
data was collected (1974). The statistics profession inside Defra could be found to 
be in breach of the existing Code of Practice.  
 
Solution 
We will publish our privacy impact assessment alongside the publication of this data 
archive, to show people the steps taken prior to publishing this data as open data. 
Demonstrating a rigorous risk process, and being open and transparent about 
internal consultation, changes to the data and risks considered, can be powerful 
mechanisms for engendering trust in government.  
 
We will also work with the Defra communications directorate to prepare a set of 
reactive messages in the event concerns are raised about Defra’s collection and 
publication of the survey results. Importantly, this release should be positioned as a 
positive, people-friendly data publication - an opportunity to explore food and drink 
trends around Britain from the 1970s - 2000. 
Step six: sign off 
Who approves the privacy risks involved in the project? 
 
For this project, a data governance group has been assembled comprising: 
●  the senior responsible officer for data within Defra 
● the Head of the Statistics Profession in Defra 
● The Director for Food & Farming and 

● the Director General for Evidence 
 
This group must review the PIA, discuss it with the Family Food Survey team and 
approve publication of the data archive as it recommends.  
Defra will look to establish a permanent sub-committee of the Data Governance 
Board - an internal board helping to implement the wider Defra Data Programme - to 
review future releases that may involve some personal data or other risk.  
Step seven: integrate PIA outcomes back into the project plan 
The Food and Trade statistics team owns this data and the Food and Trade 
Statistician is the current asset owner. The Food and Trade Statistician has 
responsibility to ensure publication conforms with the recommendations of the 
overall assessment as signed off by the data governance group. 
Preparing the next tranche of data (2001 - present) for release 
This PIA concerns the preparation of Family Food data from 1974 - 2000 for release. 
Following the 18th February, the project team will begin preparing for the release of 
data to the present day, collected as part of the Office of National Statistics (ONS) 
Living Costs & Food Survey. As the data from 2001 to present is jointly administered 
by ONS and Defra, a different governance process will be required to approve sign 
off of the data for publication. 
 
Defra expects that the more recent data may require additional disclosure control, 
due to its age and the increasing availability of public information sources (e.g. social 
media) that may increase the risk of identification. Defra will begin with the data 
specification agreed on for its 1974 - 2000 release, and conduct a penetration test of 
the more recent data after it has been processed according to this specification. 
Defra will also continue to engage with external users and provide updates to 
changes to the data set for publication as a result of this process.