Food and You 2: Technical Report: Fieldwork and response rates

Letters and reminders

Letters and reminder strategy

The mailing approach follows Ipsos’ standard push-to-web methodology:

1. An initial invitation letter is issued to sampled addresses inviting up to two adults to go online and complete the online questionnaire.  
2. The first reminder letter is issued around 2 weeks after the initial invite. issued. Reminder letters are only sent to non-responding addresses and addresses where one adult has completed the online questionnaire but not a second adult (the presence of an eligible second adult is determined in the first questionnaire). 
3. The second reminder letter is only sent to non-responding addresses and addresses where one adult has completed the online questionnaire but not a second adult. All of these letters are accompanied by one or two postal questionnaires, to allow those who cannot access the internet, and those who may be less comfortable completing online questionnaires, to take part. Those in Wales receive one questionnaire in English and one in Welsh. Further detail is provided in the section on the postal questionnaire. 
4. A final reminder letter is issued to non-responding addresses. 

When the reserve sample is used, invitation letters are sent around a month after the initial mailing with the first reminder sent to non-responding households about a fortnight later. The second reminder, which includes the postal questionnaire is sent about another two weeks later. A decision about whether issuing the final reminder letter to reserve sample addresses is necessary depends on the response rate. However, as a result of the reserve sample being issued, the survey must remain open for both main and reserve sample addresses for an extended period. 

Letter design 

The principles for designing the invitation and reminder letters, which have been kept substantially the same across waves, are primarily based on the Tailored Design Method, which was initially developed by Don A Dillman and described in ‘Internet, Phone, Mail and Mixed-Mode Surveys: The Tailored Design Method’ (2014) ^{(footnote 1)}.  A host of other literature and best practice based on previous studies (mainly the Active Lives survey and Labour Force Survey) were also used to inform the design. The main aim of the letters is to provide all the relevant information a participant requires to complete the survey, and to answer immediate questions which they may have. 

Our guiding principles for designing the letters are:

• Use simple and easy to understand language, with no unnecessary complicated text
• Cover key messages that need to be conveyed in the letters including:

(a)    Importance
(b)    Motivators for taking part
(c)    How to take part
(d)    Your personal data are safe

Importance is conveyed in all four letters in the following ways:

• FSA, Defra / FSS logos are prominent
• Visual clutter which could distract from the logos and the importance of the survey is avoided
• Professional letter format with address of recipient and full date
• Signed by someone with authority (signified by their job title and organisation details) 
• Highlighted key messages in the text; using these to break up the text makes it easier to read

The main motivational statements varies across the four letters, with the aim of increasing the likelihood of converting non-respondents:

• 1st letter: It’s easy to take part and why take part
• 2nd letter: Taking part will benefit you and your community
• 3rd letter: We want to hear from as many people as possible
• 4th letter: This is the last chance to have your say
• In addition, all letters place a degree of emphasis on the financial motivator for taking part – receiving a £10 gift voucher 

In addition to this the letters also provide key information about Ipsos and the Food Standards Agency / Food Standards Scotland and contact details for Ipsos should the participant have any queries about the survey.

Online questionnaire

The Food and You 2 survey is hosted using Ipsos’ global Dimensions platform within Rackspace, a managed hosting facility and Europe’s most successful managed hosting company. The security features offered by Rackspace, and Ipsos are listed below:

At Rackspace:

• Rackspace has SAS 70 type II and Safe Harbor certifications and operates management systems which are compliant to International standards (IS09001, ISO27001);
• The servers and network infrastructure are physically located in England;
• The servers and network components are fully redundant;
• Rackspace guarantees recovery of hardware failures within one hour.

At Ipsos:

All applications and data for Dimensions are managed by Ipsos. Access to Dimensions’ questionnaires and data are password protected. Only a small number of online survey experts have access. Survey data and any participants personal information are stored in separate databases at Ipsos.

Survey URL

A dedicated URL that specifically includes ‘food and you’ for the Food and You 2 survey is used. When deciding on the URL we wanted to choose an address that was short enough for participants to remember and one which would not easily be mis-typed. It also needed to give some indication of survey content.

Online questionnaire accessibility

The online questionnaire is made to be as accessible as possible to participants. Key to this is offering those in Wales the opportunity to complete the survey in Welsh (in line with the Welsh Language Act 1993). Participants can request to complete the survey in another language by calling the Food and You 2 survey helpline, or by asking someone to complete it on their behalf.

The Food and You 2 survey is designed to be accessed using a range of devices, including desktop computers, laptops, tablets and smart phones. The survey is designed with a ‘mobile first’ approach to minimise drop offs and improve response rates. A ‘mobile first’ approach means that the online questionnaire is designed with smart phone users in mind initially, as this is increasingly how participants choose to access online questionnaires. Additionally, the online questionnaire is designed in a way that make it easy for people to adjust colour contrasts and increase font size. 

Topline data checks

Once the online survey is in field and a sufficient number of responses have been received, topline data are reviewed to ensure no errors are detected with the filtering. Whilst extensive testing is carried out prior to fieldwork launch, on occasion unusual combinations of answers, particularly those involving non-valid answers, mean that minor errors are identified. By reviewing the data early on in fieldwork such errors can be identified and corrected.  

Postal questionnaire

At the second reminder (Mailing 3) non-responding households, and non-responding individuals in multi-adult households, are sent postal questionnaires, according to the country they live in.

In most waves there are two postal versions for each country. For these waves person 1 and person 2 at each address is assigned either version A or B on a quasi-random basis. Non-responding households are sent version A and B to complete (in Wales, an English and Welsh version are sent – where version A or B are randomly assigned to either language). Where only one completed questionnaire from a multi-adult household is received, the version which has not yet been completed, is sent to the person who has not responded (in Wales, the version that has not yet been completed is sent in both English and Welsh).  

In waves where there is only one version of the postal questionnaire for each country, non-responding households are sent two of the same postal questionnaire to complete (in Wales, this is sent in both English and Welsh). Where we have received only one completed questionnaire from a multi-adult household, one postal questionnaire is sent to the person who has not responded (in Wales, this is sent in both English and Welsh).

Storage of scanned images and survey results

All scanned images and survey data are stored securely. Only relevant staff have access to these for data processing. Images are securely deleted after fieldwork and electronic coding of postal responses has been completed.

Vouchers for participants 

Participants are offered a £10 gift voucher as a thank you for taking part in the survey.

Participants who complete the survey online who wish to receive a voucher enter their email address at the end of the survey. Participants are then emailed a Love2shop e-voucher of the nominal amount which they can redeem online at the Love2Shop website.

Those who complete the postal questionnaire are given the choice of receiving a Love2shop e-voucher or paper Love2shop voucher via post, either of which can be redeemed at a wide range of high street stores. Participants are asked to give their name in order to address the voucher to the correct person, but even without a name a voucher is sent to that address.

Handling queries

The survey website provides information about the survey and includes a list of frequently asked questions (FAQs) which have been developed based on similar studies.

Additionally, a dedicated freephone telephone helpline and email address are set up allowing participants to contact Ipsos if they have any queries about the survey. Telephone queries are first recorded by an answer machine and a member of the research team returns the call when they have identified an appropriate solution. Emails sent to the Food and You 2 survey inbox are first answered with automatic responses, which include the commonly asked questions and answers. Each query is then followed up individually within five working days.

Response rates

Response rates can be found in the accompanying technical report tables.