Six per cent of all adults in the UK have no internet access at home (Ofcom, 2026, fieldwork September to November 2025). Whether that gap ruins your survey or matters not at all depends entirely on whom you want to ask.
An online survey is a standardised survey in which participants complete a questionnaire themselves through a link in their browser, without anyone asking the questions aloud. Online surveys are quick, cheap and hand you the data in digital form straight away, yet they only ever reach people who are online. By the end of this piece you can decide for your own project whether the online mode fits.
📌 The key points at a glance
- An online survey is a standardised survey run through a link.
- The upside: low cost, short field time, instantly digital data.
- The drawback: an online survey reaches only people with internet access.
- Six per cent of UK adults lack internet access at home.
- A large number of responses does not create representativeness.
Create a survey for free
With empirio.ai you can create a modern online survey in minutes — with hosting in the EU.
- AI-built survey
- Adjust by drag & drop
- Real-time analysis
What is an online survey?
An online survey is a standardised survey whose questionnaire is filled in over the internet: the person being surveyed opens a link in a browser, answers the questions with nobody else present and submits the form.
In the methodological literature the online survey goes by the abbreviation CAWI (= computer-assisted web interviewing). What that names is not the technology but the mode of data collection: whoever fills in the questionnaire does so without a counterpart and at a pace they set themselves. Both the strengths and the weaknesses of this form grow out of that single property, and neither can be had without the other.
Three terms get mixed up in everyday use, and a methods chapter keeps them apart:
| Term | What it refers to |
|---|---|
| Survey | the method of data collection as such, whatever the channel |
| Online survey | the survey in internet mode, without an interviewer |
| Questionnaire | the instrument holding the questions and answer options |
An online survey is usually quantitative in design, because a standardised questionnaire puts the same questions to everyone in the same order. Qualitative access through open text boxes is possible, yet it replaces no interview. How the two approaches differ is set out in the piece on qualitative and quantitative surveys.
An online survey is not a separate type of questionnaire. Online is simply a way of delivering the same questionnaire.
What are the advantages of an online survey?
The advantages of an online survey lie in cost, speed and data quality: there are no interviewer fees and no postage, the field time shrinks from weeks to days, and the answers arrive as a finished dataset without anyone typing them up.
Wolfgang Bandilla names exactly these points in the GESIS Survey Guidelines (2015) as the reasons the online mode has prevailed: short field times, immediate storage of the answers, complex routing and the option of building in multimedia elements. Rather than a technical convenience, all of that is a methodological gain, because every working step that falls away is a step at which no error can arise.
What the online mode actually delivers
- The questionnaire is built once and completed any number of times.
- Filters and skip rules run automatically, so nobody lands in the wrong question.
- The answers are ready for analysis as a dataset straight away.
- On sensitive topics people answer more openly with no counterpart present.
- Images, videos and sliders can be built into the form.
Losing the counterpart is the methodologically most interesting of these advantages. Because no interviewer sits in the room and no voice reacts on the telephone, the pressure to give a socially desirable answer falls away. On questions about income, health, conflict in a team or a person’s own behaviour that effect is well documented, and for many projects it is the strongest reason to collect data online at all.
What are the drawbacks of an online survey?
The central drawback of an online survey is its access: only somebody who is online, who receives the link and who decides to take part can do so. Everything else, from drop-offs to unserious answers, follows from that one property.
What you take on in exchange
- Queries go unanswered, because nobody is there to explain a question.
- Who actually filled in the form cannot be verified.
- Drop-offs mid-questionnaire are more frequent than in supervised surveys.
- People without internet access or a suitable device fall out entirely.
- Without an invitation list, those addressed decide themselves whether to join.
Uncertainty about who really completed the form can be softened, never dissolved. Sending personalised links at least tells you which invitation was used, though not who sat in front of the screen. For a dissertation or a quick mood check that is generally enough, for a survey with legal consequences it is not.
⚠️ Careful
A common mistake is the combination of an open link and the claim that the sample was drawn at random. Anyone who shares the link freely has self-selection and says so in the methods chapter. The way out is a fixed invitation list with personal links.
Online, postal, telephone or face to face: which survey mode fits?
The four classic survey modes differ above all in whom they reach and what they cost: the online survey is the fastest and cheapest, the face-to-face interview the most expensive and most thorough, with the postal and telephone forms in between.
Bandilla (2015) recommends in the GESIS Survey Guidelines that where a target group has insufficient internet access, you switch to a postal or face-to-face mode, because neither carries a comparable barrier to access. Choosing a mode is therefore not a matter of taste but a consequence of whom you want to ask. For the UK, the National Centre for Social Research sets out its own methodological work on transforming online surveys.
| Survey mode | Its strength | Its limit |
|---|---|---|
| Online survey | cheap, field time in days, data digital at once | reaches only people with internet access |
| Postal survey | reaches offline households through an address frame | postage, weeks of returns, answers must be typed up |
| Telephone survey | random selection through generated numbers is possible | interviewer costs, no visuals, falling contact rates |
| Face-to-face survey | long questionnaires, follow-up questions and observation | most expensive mode, interviewers shape the answer |
For many projects the choice of mode is settled faster than it sounds:
| Your project | The mode that fits |
|---|---|
| Survey of students for a dissertation | online, the target group is reachable almost in full |
| Staff survey inside a company | online, provided everyone has access at their workplace |
| Survey of people aged over 75 | postal or in person, online loses a relevant share |
| Population survey claiming representativeness | random sample, in practice usually mixed mode |
| Short mood check in a club | online, no other mode is worth the effort |
Mixed mode means combining several modes inside the same study. The GESIS Panel, for instance, surveys its participants online and brings people who do not use the internet in by post, so that both groups end up in the same dataset (Bandilla, 2015). For a dissertation that effort is usually too great, for a public body or a research institute it is the standard route.
Create a survey for free
With empirio.ai you can create a modern online survey in minutes — with hosting in the EU.
- AI-built survey
- Adjust by drag & drop
- Real-time analysis
When an online survey is the wrong choice
An online survey is the wrong choice as soon as a noticeable part of your target group is not online. Survey methodology calls that the coverage problem: the inadequate overlap between the intended population (= everyone you want to make a statement about) and the group that is able to take part at all.
Generally speaking, a national average helps little with that question. Six per cent of all UK adults have no internet access at home, and 20 per cent of those who are online use a smartphone as their only device (Ofcom, 2026). Spread across the population, though, that gap sits very unevenly, and the uneven spread is what decides your project.
| Ofcom finding for UK adults | Share |
|---|---|
| Adults with no internet access at home | 6 per cent |
| Online adults using a smartphone only | 20 per cent |
| The offline group that is aged 75 or over | 66 per cent |
| The offline group that is aged 65 to 74 | 17 per cent |
Source: Ofcom, Adults’ Media Use and Attitudes Report, published 2 April 2026, fieldwork September to November 2025, 7,533 adults aged 16 and over. The last two rows describe how the offline group is made up, not the share of each age band that is offline. As of August 2026, subject to change.
Read the last two rows carefully, because they are the most misquoted figures in this whole area. Ofcom describes the composition of the offline group, so two thirds of the people without internet access at home are aged 75 or over. Turning that into “66 per cent of over-75s are offline” would be a different claim altogether, and a false one.
A second gap sits in the statistics themselves, and the gap is a finding in its own right. The Office for National Statistics discontinued its series on internet users, whose last figure dates from 2020, so the UK has no up-to-date official statistic on people who never use the internet. Anyone planning a survey among older or less connected groups therefore budgets for a second channel from the outset, instead of leaning on a single headline percentage.
The same arithmetic applies to any other subgroup. In a survey of people without formal qualifications, of people needing care or of residents in institutions, the share reachable online lies well below the national figure. Among students, office staff or club members under 60, the coverage problem plays practically no role.
Does a high number of responses make a survey representative?
No, a high number of responses does not make an online survey representative. A survey becomes representative through the way its participants are selected and not through its size: they have to be drawn at random from the population, otherwise even a large sample stays skewed.
Bandilla (2015) names in the GESIS Survey Guidelines the reason this is particularly hard online: for the population as a whole there is no complete, currently valid list of people with internet access, and therefore no list of email addresses from which a random sample could be drawn. Telephone surveys can generate random numbers artificially, whereas email addresses allow nothing comparable.
Open calls for participation and self-recruited volunteer panels fail for the same reason. Bandilla cites Schnell (2012) on this, with the verdict that samples of that kind are not suited to serious population surveys. Nevertheless the online mode works well for experiments and hypothesis tests, because what counts there is the random allocation to experimental groups and not the selection of respondents.
💡 Tip
For a dissertation a non-random sample is rarely a problem, as long as you name it. A sentence such as “The sample is a convenience sample, so the results cannot be generalised to the population” costs you no marks, and it will not trip you up in the viva either. Concealing it costs you some.
How many participants you actually need, and what else representativeness hangs on, is set out at length in the piece on the representative survey.
Common mistakes in online surveys
Most mistakes in online surveys are made long before the analysis: in the way the target group is cut, the way the questionnaire is built and the way the invitation goes out. Four of them turn up especially often in dissertations and in professional practice.
All four can be fixed before the link goes out and not afterwards. So the half day that a proper pretest with five test readers costs is almost always worth it.
The questionnaire is unusable on a phone
A large share of responses now comes from smartphones, and rating grids with seven columns simply do not work there. The consequence is not an empty dataset but a poor one: somebody battling through an unreadable grid ends up clicking the middle column every time. Open every questionnaire once on your own phone before you send it.
The invitation promises anonymity while the tool still records
Anonymity is a setting in the survey tool, not a statement of intent in the invitation text. As long as email capture, a mandatory account or IP storage is switched on, the survey is not anonymous, whatever the invitation says. Which settings to check is covered in the piece on data protection in surveys.
Anonymity is also not the only obligation. As soon as a university, an employer or a club stands behind the survey, UK GDPR requires a contract with the tool provider, and the Information Commissioner’s Office sets out when that contract is needed. Its page carries a notice that the guidance is under review following the Data (Use and Access) Act, so check the current wording, and for student work ask your supervisor or the research ethics committee what your institution expects.
The questionnaire is too long
Drop-offs are not spread at random: whoever quits differs systematically from those who see it through, and that difference distorts the result. Ten minutes is the upper limit for most projects, and closer to five where participation is voluntary and unrewarded. Cutting questions hurts less than a sample made up only of the unusually motivated.
The field time is set too short
A field time of 48 hours excludes everyone who is on holiday, on shift work or ill during those two days. What arises is the same systematic bias as with an overlong questionnaire, only less visible. Two weeks with one friendly reminder after the first week is a good rule of thumb and costs nothing but patience.
Conclusion
An online survey is the right choice for the great majority of projects, because it is fast, cheap and low in error, and it is the wrong one as soon as a relevant part of the target group is not online. Decide first whom you want to ask, and only then how. If you do collect data online, name the self-selection openly rather than stepping around it: a study that knows its limits is worth more than one that hides them.
Where to go next
- Ready to build the questionnaire? Questionnaire design: how to create a questionnaire
- Looking for a template to adapt? Templates and examples for surveys
- Wondering how many participants are enough? When an online survey is representative
- Want a better response rate? Tips for the perfect online survey
- Writing the methods chapter right now? Empirical research: definition, methods, guide
Want to launch your online survey today?
With empirio.ai, an online survey tool from Germany, you build the questionnaire in a few steps, keep the data hosted in the EU and analyse the answers inside the tool.