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Survey: Definition, Types and When It Is Compulsory

We show you how a survey differs from observation and experiment, which types and levels of standardisation exist, and which UK surveys you are legally required to answer.

Author at empirio.ai - Maria Malzewby Maria MalzewUpdated 23 August 2026Reading time 11 min

Every ten years, everyone in England and Wales has to answer a survey whether they want to or not. When you run your own survey for a dissertation, the opposite applies: anyone can stop halfway through without giving a reason.

A survey is a data collection method in which people give information about their opinions, attitudes, knowledge or behaviour, either in writing or in conversation. It is chosen whenever the subject of the research cannot be observed and is only accessible through language, such as motives or values. By the end you will know which type of survey fits your research question and how to spot that the method is the wrong one.


📌 The key points at a glance

  • A survey collects data through language, not through observation.
  • Standardised, semi-standardised, non-standardised: three levels, three routes.
  • Quantitative and standardised are not the same thing.
  • The UK census is compulsory, ONS household surveys are voluntary.
  • Answers can be biased even when everyone is honest.

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Survey: definition and how it differs from other methods

A survey is a planned and purposeful communication process in which a researcher asks questions and a respondent answers them, so that the answers can be turned into data in a systematic way. Across the social sciences, business studies and psychology, the survey is the most widely used data collection method there is.

So why ask instead of simply watching? The rule of thumb in empirical research is that a survey is the right choice whenever the thing you care about cannot be observed and only becomes accessible through language. Opinions, attitudes, values and emotions all fall into that category. If you want to know how often someone visits the university canteen, count. If you want to know why they avoid it, ask.

Overview of the four empirical data collection methods: survey, observation, experiment and content analysis

Alongside the survey there are three other routes to data. Which one fits is not decided by effort or budget, but by where the information you are after actually sits.

MethodWhat it capturesWhere it runs out
Surveyopinions, attitudes, motives, reported behaviouranything respondents do not know or will not say
Observationactual behaviour in a real situationthe reasons and intentions behind that behaviour
Experimentthe effect of one deliberately changed conditioneveryday realism, because conditions are artificial
Content analysisfeatures of existing texts, images or videosanything that was never recorded

The table also makes the single biggest caveat visible: a survey produces self-reports, not measurements. People misremember, guess, or rate themselves more kindly than the facts allow. Subjective judgements and objective facts are therefore not interchangeable, however carefully the questionnaire is written.

A survey does not measure what people do. It records what people say about it.

Types of survey: quantitative and qualitative

Surveys fall into two broad types: the quantitative survey, which asks many people the same questions and is analysed statistically, and the qualitative survey, which lets a small number of people speak at length. The difference is not the number of participants alone, it is what the study is trying to find out.

A quantitative survey tests assumptions that already exist. A qualitative survey looks for patterns nobody has put into words yet. If you already have a hypothesis, count. If you do not, listen. The two combine well, for instance when a handful of interviews supply the wording for a later questionnaire.

Quantitative survey: measuring and comparing

The quantitative survey uses one identical questionnaire for everyone, online, on paper, by telephone or face to face. Most of it consists of closed questions with fixed answer options. Because conditions stay the same for every respondent, the answers can be added up, split into groups and compared with one another. How a quantitative survey is built in detail is covered in its own article.

What a quantitative survey delivers

  • It produces numbers that can be tested statistically.
  • It reaches large groups at a reasonable cost.
  • It keeps the survey situation constant for everyone.
  • It allows comparison across several points in time.

Qualitative survey: understanding and reconstructing

The qualitative survey runs as a conversation, usually a semi-structured, expert or narrative interview, often with a single-figure number of participants. The questions are open, and the respondent helps decide which points to expand on. That is precisely where the value sits: what someone chooses to stress or leave out is itself a finding. Analysing those conversations is covered in the article on the qualitative survey.

What a qualitative survey delivers

  • It opens up topics with no established theory behind them.
  • It allows follow-up questions during the conversation.
  • It makes reasoning and contradictions visible.
  • It works with few, deliberately chosen cases.

Level of standardisation: standardised, semi-structured or open

The level of standardisation describes how far the wording and order of the questions are fixed in advance. Methodology distinguishes three levels, and the choice belongs to the research design, not to the interviewer sitting in the room.

LevelHow the questions runWhat the level is good for
Standardisedwording, order and answer options are identical for everyonetesting hypotheses, statistical analysis
Semi-structureda topic guide fixes themes and order, the phrasing stays freeinterviewing experts, reaching known points quickly
Non-standardisedonly the topic is fixed, the conversation takes its own coursebuilding theory, exploring unmapped ground

You will often read that standardised is simply another word for quantitative. That is not quite right. The level of standardisation and the question of numbers versus text are two separate axes. The semi-structured interview is the clearest example: it follows a fixed topic guide and still analyses text rather than numbers.

The practical value of the distinction shows up when you write the instrument. A standardised questionnaire has to be finished before the first invitation goes out, because any later change destroys comparability. A topic guide may still grow between the second and the third interview, as long as the change is documented in the methodology chapter. Supervisors and viva panels ask about exactly that. Further guidance sits in the article on objectivity, reliability and validity.

Kinds of survey: by mode, number of topics and frequency

Kinds of survey differ in three respects above all: the route the questions travel, how many topics one questionnaire covers, and how often the same study is repeated. On top of that sits the distinction between direct and indirect questioning.

The three classifications do not compete, they stack. One study can be telephone-based, single-topic and set up as a panel at the same time. For a methodology chapter that means naming all three axes, otherwise the design of the survey stays unclear to the reader.

Survey modes: face to face, postal, telephone, online

A face-to-face survey is the classic interview in person, a postal survey uses a paper questionnaire sent by mail, a telephone survey runs as a call, and an online survey travels as a link in a browser. Four things decide which mode fits. A face-to-face interview tolerates long questionnaires but costs the most. Telephone and internet deliver results quickly, post and personal interviews take longer. Images or video as stimuli work well in person and online, and not at all on the phone. Strengths and limits of the digital route are covered in the article on the online survey.

💡 Tip

Offer two routes when one group would otherwise drop out. If you launch online and also make paper questionnaires available, people without reliable internet access stay in the sample, and you avoid having to explain the gap in your methodology chapter later.

Kinds of survey by topics and frequency: omnibus, panel and wave

A single-topic survey covers exactly one subject, while an omnibus survey bundles several clients into one questionnaire and splits the cost between them. By frequency, market research separates the one-off survey from the repeated survey, and repetition itself splits in two: a panel survey asks the same people every time, a wave survey asks different people each round. The difference matters, because only a panel shows change within individual people. A wave shows change in the average.

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Is taking part in a survey voluntary in the UK?

Taking part in a survey in the UK is usually voluntary, but not always. Two exceptions carry a legal duty: the census, and most business surveys run by the Office for National Statistics. Everything else, including ONS household surveys, is a request rather than an obligation.

The Office for National Statistics states that the Census Act 1920 makes answering the census questions mandatory for everyone in England and Wales, and that failing to complete a census questionnaire is a criminal offence punishable by a fine of up to 1,000 pounds and a criminal record. Three questions are exempt from that penalty: religion, sexual orientation and gender identity. The last census took place on 21 March 2021, and in July 2025 the government commissioned a further mandatory whole-population census for 2031.

⚠️ Careful

Household surveys are a different matter. For the Labour Force Survey the Office for National Statistics writes that no-one has to take part if they do not want to, and its Respondent Charter promises to be honest about participation being voluntary. Business surveys reverse that again: under the Statistics of Trade Act 1947 most are legally required, with fines of up to 2,500 pounds for non-compliance and no exemption or appeal process (as at August 2026).

For your own survey none of this applies. A study for a dissertation, a charity or a company is always voluntary, and that belongs in the invitation text. Alongside it goes an explanation of what data you store and for how long, since UK GDPR requires transparency before collection begins. The article on data protection in surveys covers the detail.

Source: Office for National Statistics, Census legislation and policy (accessed 23 August 2026).

Common mistakes in surveys

The most common mistakes in a survey are not made during analysis. They are made much earlier, while the questions are being written and the method is being chosen. The core problem has a name: validity. A survey may simply not be measuring what it set out to measure.

Four patterns come up again and again. All four are avoidable, but only before the invitations go out.

Social desirability shifts the answers

People answer the way they believe will look good. On questions about exercise, alcohol, charitable giving or environmental behaviour, the answers therefore come out consistently more flattering than the actual behaviour. Anonymity reduces the effect noticeably, because no answer can be traced back to a person. A staff survey whose results a line manager could read individually mostly measures caution.

Questions about the past meet patchy memory

Questions about the past assume that respondents remember correctly. For rare events that works, for everyday ones it rarely does. Ask how often someone exercised over the past year and you get an estimate, not a number. Short reference periods and fixed anchors make the answer more reliable, for example over the past seven days rather than normally.

Question order and answer options steer the result

The order of the questions and the choice of answer options shape responses systematically. A question about overall satisfaction reads differently after five questions about problems. If the option that actually applies is missing from a list, respondents pick the nearest one and the analysis shows a result nobody ever meant. The article on creating a questionnaire goes into this in detail.

The survey was the wrong method

Some questions cannot sensibly be asked at all. If you want to know how long visitors stand in front of an exhibit, measure rather than ask, because nobody knows that number about themselves. Unconscious processes and heavily automated behaviour are equally out of reach for a survey. Observation, an experiment or existing data will give the sounder answer.

Conclusion

A survey is strong when the subject is opinions, reasons and judgements, and weak everywhere something can be measured directly. Before you write the first question, settle two things in this order: whether a survey is the right method at all, and how much standardisation your research question can carry. Everything else, from mode to analysis, follows from those two answers.

Where to go next


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Frequently asked questions

A survey in research means asking people about their opinions, attitudes, knowledge or behaviour, either in writing or in conversation. A survey is therefore a data collection method, and the most widely used one in the social sciences. It is chosen when the subject cannot be observed and is only accessible through language.

A survey is the whole research exercise, from choosing the sample to analysing the answers. A questionnaire is the instrument used inside it: the actual list of questions and answer options. Every questionnaire belongs to a survey, but a survey can also run as an interview without any questionnaire at all.

A standardised survey asks every participant the same questions, in the same wording, in the same order and with the same answer options. Conditions stay identical for everyone, so the answers can be counted, compared and tested statistically. Standardised surveys belong to hypothesis-testing research.

Yes, the census in England and Wales is compulsory. The Census Act 1920 makes answering the questions mandatory, and the Office for National Statistics states that failing to complete it can lead to a fine of up to 1,000 pounds and a criminal record. Questions on religion, sexual orientation and gender identity are exempt (as at August 2026).

Households do not. The Office for National Statistics states plainly for the Labour Force Survey that no-one has to take part if they do not want to, and its Respondent Charter promises honesty about participation being voluntary. Businesses are different: most ONS business surveys are legally required under the Statistics of Trade Act 1947.

A survey reaches information that would otherwise stay out of reach: opinions, motives, attitudes and judgements. Compared with observation and experiment it is fast and inexpensive, it scales to large groups, and it can be repeated to show change over time. Most of the effort sits in the preparation, not the fieldwork.

In psychology a survey is a method for capturing experience, attitudes and self-assessment, usually through standardised questionnaires or interviews. It produces self-reports rather than objective measurements, which is why it is often combined with behavioural observation or reaction-time tasks. Objectivity, reliability and validity decide how much the results are worth.

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