Before a respondent answers a single question in your survey, they read your cover letter. In an online survey, this is usually the first screen or the invitation email. In a paper survey, it is the letter attached to the front of the questionnaire. In just a few seconds, respondents decide whether your study is worth their time.
A good cover letter improves response rates, builds trust and meets ethical requirements for informed consent. A weak one can make your survey look like spam, confuse respondents about what is being asked, or raise ethics concerns. This post explains what to include, how to write it, and common mistakes to avoid, with a template you can adapt.
What is a survey cover letter?
A survey cover letter (also called an invitation letter, participant information letter or introduction page) is a short document that introduces your study to potential respondents. It explains who you are, why you are doing the research, what participation involves, and how their information will be protected.
Depending on your institution and ethics committee, the cover letter may be combined with a full participant information sheet and consent statement, or it may be a shorter introduction that links to a separate information sheet. Always check what your ethics approval requires.
Why the cover letter matters
1. It affects response rates
People receive many requests to complete surveys. A clear, respectful and credible invitation helps your survey stand out. Research on survey methodology consistently shows that the way a request is presented influences whether people take part.
2. It supports informed consent
Participants need enough information to make a free and informed decision about taking part. The cover letter is often the main place where this information is provided in survey research.
3. It sets expectations
When respondents know how long the survey takes and what kinds of questions to expect, they are less likely to drop out halfway through.
4. It builds trust
Clear information about who is running the study, who approved it and how data is protected reassures respondents that the survey is genuine and safe.
What to include in your cover letter
1. A clear, personal greeting
If possible, address respondents by name or by a relevant group, such as "Dear nursing colleague" or "Dear small business owner". A personal greeting feels more respectful than "To whom it may concern".
2. Who you are
State your name, position (for example, PhD candidate), department and university. Mention your supervisor if appropriate. This establishes credibility.
3. The purpose of the study
Explain in one or two sentences what the study is about and why it matters. Use plain language, not the technical wording of your research questions. For example: "This study explores how teachers use digital tools in their classrooms and what support would help them."
4. Why they were selected
Tell respondents why they are being invited: "You are receiving this invitation because you are a registered member of the national teachers' association." This helps them understand the relevance of the survey to them.
5. What participation involves
Be specific:
- What they will do (complete an online questionnaire).
- How long it will take (give an honest estimate based on your pilot).
- What kinds of questions are included, especially if any are sensitive.
- Whether there are any follow-up stages.
6. Voluntary participation and right to withdraw
Make clear that participation is voluntary, that they can skip questions they do not want to answer (if your design allows it), and that they can stop at any time. Explain whether data can be withdrawn after submission. For fully anonymous surveys, withdrawal after submission is often not possible because responses cannot be identified; say this clearly.
7. Confidentiality and anonymity
Explain the difference carefully:
- Anonymous: you cannot link responses to individuals at all.
- Confidential: you may know who responded, but you will not reveal identities or share identifiable data.
Do not promise anonymity if you collect email addresses, IP addresses or other identifying information. Describe how data will be stored, who can access it, how long it will be kept, and how results will be reported (for example, only in aggregate form).
8. Risks and benefits
Briefly describe any potential risks or discomfort, such as questions on sensitive topics, and how you will minimise them. Mention realistic benefits, such as contributing to improved policies or practices. Avoid overstating benefits.
9. Incentives (if any)
If you offer an incentive, such as a small voucher or a prize draw, explain the conditions clearly and make sure the incentive has ethics approval.
10. Ethics approval
State that the study has been approved by your institution's ethics committee and give the approval reference number if required.
11. Contact information
Provide your contact details and those of your supervisor. Include a contact for the ethics office for complaints or concerns about how the study is conducted.
12. Consent statement
For online surveys, include a clear consent statement, such as: "By clicking 'I agree' below, I confirm that I have read the information above, I am 18 years or older, and I agree to take part in this study." Follow your ethics committee's required wording.
13. Thank you
End by thanking respondents for their time. A sincere thank you encourages participation.
Writing style tips
- Keep it short. One page, or one screen, is ideal for the main message. Put extra details in a linked information sheet if allowed.
- Use plain language. Write for your respondents, not for your examiners. Avoid jargon and acronyms.
- Use short paragraphs and headings. Many people skim on mobile screens.
- Be honest about time. Underestimating completion time damages trust and increases dropout.
- Use a friendly, respectful tone. Avoid pressure or guilt.
- Proofread carefully. Spelling mistakes reduce credibility.
A simple template you can adapt
Subject: Invitation to take part in a short survey on [topic]
Dear [name or group],
My name is [name], and I am a PhD candidate at [department, university], supervised by [supervisor]. I am conducting a study on [topic in plain language]. The aim is to understand [purpose] so that [benefit].
You are invited because [reason for selection]. Taking part involves completing an online questionnaire that takes about [X] minutes. The questions ask about [general content].
Participation is completely voluntary. You may skip any question or stop at any time without giving a reason. [Explain anonymity or confidentiality.] Your responses will be stored securely on [storage], kept for [period], and reported only in combined form.
This study has been approved by [ethics committee], reference [number]. If you have any questions, please contact me at [email] or my supervisor at [email]. For concerns about the conduct of the study, please contact [ethics office contact].
Thank you very much for considering this invitation. Your views are valuable to this research.
[Name, title, university]
Special considerations
Online surveys
Place the most important information on the first screen. Include a visible progress bar in the survey itself. Test how the invitation looks on mobile phones. Use your university email address and avoid words that may trigger spam filters.
Organisational surveys
If you are surveying employees through their organisation, clarify that participation is independent of their employer, that managers will not see individual responses, and that choosing not to take part will not affect their job. This is essential for honest answers and for ethics.
Reminder messages
Reminders are a proven way to increase responses. Plan one or two polite reminders, each shorter than the original invitation, and stop sending reminders to people who have already responded if your system allows tracking. Get ethics approval for reminder wording too.
Different languages
If your survey is translated, translate the cover letter with the same care as the questionnaire, and make sure consent information is equally clear in every version.
Weak vs. strong opening lines
The first two sentences of your invitation matter most, because many people decide whether to continue reading based on them alone. Compare these examples:
Weak: "I am conducting research for my PhD thesis and need respondents to complete my questionnaire. Please help me by filling it in."
This opening focuses on the researcher's needs, not the respondent's interest. It does not say what the study is about or why it matters.
Stronger: "Nurses across the country are facing heavier workloads than ever. This short survey, run by researchers at [university], asks for your experience so that hospitals can design better support for nursing staff."
This version connects immediately with the respondent's situation, names a credible institution and explains the benefit.
Weak: "The purpose of this study is to examine the moderating role of perceived organisational support in the relationship between workload and burnout."
This is accurate but written for an academic reader. Most respondents will not understand or care about moderating roles.
Stronger: "We want to understand how workload affects wellbeing at work, and whether support from employers makes a difference."
The meaning is the same, but the language is plain and inviting.
Pilot testing your cover letter
Include the cover letter in your pilot study. Ask a few pilot participants:
- After reading the letter, what did you think the study was about?
- Was anything unclear or worrying?
- Did you feel you had enough information to decide whether to take part?
- Was the estimated completion time accurate?
Their answers will tell you quickly whether your letter communicates what you intended. Small changes, such as moving the time estimate higher up or simplifying one paragraph, can make a noticeable difference.
Common mistakes to avoid
- Writing a long, dense letter full of academic language.
- Hiding the time commitment or underestimating it.
- Promising anonymity while collecting identifying data.
- Leaving out ethics approval details or contact information.
- Using pressure, such as implying that participation is expected by the employer.
- Forgetting to tell respondents what happens to their data.
- Not pilot testing the cover letter along with the questionnaire.
Final thoughts
Your cover letter is the front door to your survey. Make it short, clear, honest and respectful. Explain who you are, why the study matters, what participation involves, and how data will be protected. Test it along with your questionnaire, get it approved by your ethics committee, and use it consistently. A well-written cover letter will not only increase your response rate but also show respondents, and later your examiners, that your research is conducted with care.
Want feedback on your survey invitation? Share a draft (without identifying details) in the comments.