Fieldwork and response rates

Letters and reminders

Letters and reminder strategy

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

1. An initial invitation letter was issued to all sampled addresses inviting up to two adults to go online and complete the online questionnaire. This letter was mailed on the 18th October 2021 and began to arrive at sampled addresses on the 20th October 2021.

2. The first reminder letter was issued on 29th October 2021 and began to arrive at sampled addresses on 1st November 2021. Reminder invitations were sent to non-responding addresses and addresses where one adult had completed the online questionnaire but not a second adult (the presence of an eligible second adult was determined in the first questionnaire).
3. The second reminder letter was issued on the 23rd November 2021 and began to arrive at sampled addresses on 25th November 2021. This was sent to non-responding addresses and addresses where one adult had completed the online questionnaire but not a second adult. All of these letters were accompanied by one or two postal questionnaires, to allow those who could not access the internet, and those who may have been less comfortable completing online questionnaires, to take part. Those in Wales received one questionnaire in English and one in Welsh. Further detail is provided in the section on the postal questionnaire. 
4. A final reminder letter was issued on 7th December 2021 and began to arrive at sampled addresses on 9th December 2021. The survey remained open until 10th January 2022.

Letter design

The principles for designing the invitation and reminder letters, which were kept substantially the same as those used for previous waves, were primarily based on the Tailored Design Method, which was initially developed by Don A Dillman and described in depth in the book by Dillman, DA. Smyth, JD. Christian, LM. titled Internet, Phone, Mail and Mixed-Mode Surveys: The Tailored Design Method published in 2014 by Wiley.  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 was 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 were:

• use simple and easy to understand language, with no unnecessary complicated text
• to cover key messages that needed 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

a)    Importance was conveyed in all four letters in the following ways:

• FSA and Defra logos were prominent
• visual clutter which could distract from the logos and the importance of the survey was 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 made it easier to read

b)    The main motivational statements varied 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 placed a degree of emphasis on the financial motivator for taking part – receiving a £10 gift voucher 

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

Online questionnaire

The Food and You 2 Wave 4 survey was hosted using Ipsos’ global Dimensions platform in 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
• 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 access to Dimensions’ questionnaires and data was password protected. Only a small number of online survey experts had access. Survey data and any participants personal information were stored in separate databases. 

Survey URL

We used a dedicated URL that specifically included ‘food and you’ for the Food and You 2 Wave 4 survey. 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 was made to be as accessible as possible to participants. Key to this was offering the survey in Welsh (as per Welsh government guidelines) so those in Wales could complete the survey in Welsh. While we cannot be certain how many participants completed the survey in Welsh, 241 participants (6.4% of all online participants), viewed at least one page in Welsh. Participants could 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 was designed to be accessed using a range of devices, including desktop computers, laptops, tablets and smart phones. The survey was designed with a ‘mobile first’ approach to minimise drops offs and improve response rates. A ‘mobile first’ approach means that the online questionnaire was designed with smart phone users in mind initially, as this is increasingly how participants choose to access online questionnaires. Additionally, the online questionnaire was designed in a way that made it easy for people to adjust colour contrasts and increase font size. 

Break offs and questionnaire length

A total of 12% of all participants (4,261) who started the online survey did not complete it. The highest number of breakoffs were observed at two questions, which both asked participants to rank the answers they had selected at the previous question. At the first of these, EATOUT2IMP2, 81 participants discontinued with the survey and at the second, EATOUT3IMP2, a further 26 did so. 
The median completion time of those who did complete the online survey was 34 minutes and 15 seconds.

Postal questionnaire

At the second reminder (M3) non-responding households were sent postal questionnaires. Households in England and Northern Ireland where one adult had completed the questionnaire and in which a second adult had been identified were sent one postal questionnaire, otherwise non-responding households were sent two postal questionnaires in these countries. All non-responding households in Wales were sent two postal questionnaires – one in English and one in Welsh. 

Each household that received two postal questionnaires received one Eating Out Version and one Eating at Home Version postal questionnaire. Households that were sent one postal questionnaire received only one of these versions.

In total 2,051 participants completed the postal questionnaire with 1,010 completing the Eating Out Version and 1,041 completing the Eating at Home Version. There were 16 participants in Wales who completed the Welsh language postal questionnaire in total, four completed the Eating at Home version and the remaining 12 completed the Eating Out version. The number of returns of the postal questionnaire for each country is detailed in Table 2. The highest number of postal returns were received from participants in England (1,085 returns), followed by 558 in Northern Ireland and 408 in Wales. 

Table 2: The number of postal questionnaire returns, by questionnaire version, for each country

Table 3: The number of overall postal questionnaire returns for each country

Storage of scanned images and survey results

All scanned images and survey data were stored on a secure server, which is isolated from the Ipsos network and has restricted access controls. Our secure file servers are housed in server rooms/data centres with appropriate physical access controls and monitoring procedures. The network is protected by appropriate use of firewalls, DMZ and intrusion detection systems. Public facing servers are also appropriately protected and are based on a secure (minimum) two tier or, our general standard, three-tier architecture. All sub-contractors are subject to appropriate quality checks and second party information security audits by our in-house Data Compliance team. We used AES256 as a minimum standard for encryption.

Vouchers for participants

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

Participants who completed the survey online who wished to receive a voucher entered their email address at the end of the survey.

They were then emailed a Love2shop e-voucher of the nominal amount which they could redeem online at the Love2Shop website. 
Those who completed the postal questionnaire were given the choice of receiving a Love2shop e-voucher or paper Love2shop voucher via post, either of which could be redeemed at a wide range of high street stores. Participants were asked to give their name in order to address the voucher to the correct person, but even without a name a voucher would be sent to that address.

Handling queries

The survey website provided information about the survey and included a list of FAQs which had been developed based on similar studies.

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

There were around 490 queries, the majority of which were regarding when participants would receive their voucher or to opt out of the survey. Other queries included participants requesting a postal questionnaire or experiencing difficulties accessing the online survey. 

Response rates

The overall response rate for Food and You 2 Wave 4 was 28.5% with 1.44 adults participating per household on average. Of the surveys completed, 65% were online and 35% were postal questionnaires. Response rates varied by region. Table 4 shows the variation in response rate by region and country. 

Table 4: Individual level response rates by region and country

Table 5: Household level response rates by region and country

Profile of achieved sample

The table below shows the profile of those who completed the survey online and those who completed the postal questionnaires.

Table 6:  Demographic profile of survey responders

Gender

Age

This table shows that those who are 54 or younger are more likely to complete the online questionnaire than the postal questionnaire, with the opposite true for those over 55.

Ethnicity

Household size