Statistical survey
Survey methodology is the field that studies surveys, that is, the sample
Sample (statistics)
In statistics, a sample is a subset of a population. Typically, the population is very large, making a census or a complete enumeration of all the values in the population impractical or impossible. The sample represents a subset of manageable size...

 of individuals from a population with a view towards making statistical inference
Statistical inference
In statistics, statistical inference is the process of drawing conclusions from data that are subject to random variation, for example, observational errors or sampling variation...

s about the population using the sample. Polls
Opinion poll
An opinion poll, sometimes simply referred to as a poll is a survey of public opinion from a particular sample. Opinion polls are usually designed to represent the opinions of a population by conducting a series of questions and then extrapolating generalities in ratio or within confidence...

 about public opinion
Public opinion
Public opinion is the aggregate of individual attitudes or beliefs held by the adult population. Public opinion can also be defined as the complex collection of opinions of many different people and the sum of all their views....

, such as political beliefs, are reported in the news media in democracies. Other surveys are used for scientific purposes. Surveys provide important information for all kinds of research fields, e.g., marketing
Marketing is the process used to determine what products or services may be of interest to customers, and the strategy to use in sales, communications and business development. It generates the strategy that underlies sales techniques, business communication, and business developments...

 research, psychology
Psychology is the study of the mind and behavior. Its immediate goal is to understand individuals and groups by both establishing general principles and researching specific cases. For many, the ultimate goal of psychology is to benefit society...

, health professionals
Health care provider
A health care provider is an individual or an institution that provides preventive, curative, promotional or rehabilitative health care services in a systematic way to individuals, families or communities....

 and sociology
Sociology is the study of society. It is a social science—a term with which it is sometimes synonymous—which uses various methods of empirical investigation and critical analysis to develop a body of knowledge about human social activity...

. A survey may focus on different topics such as preferences (e.g., for a presidential candidate), behavior (smoking and drinking behavior), or factual information (e.g., income), depending on its purpose. Since survey research is always based on a sample of the population, the success of the research is dependent on the representativeness of the population of concern (see also sampling (statistics)
Sampling (statistics)
In statistics and survey methodology, sampling is concerned with the selection of a subset of individuals from within a population to estimate characteristics of the whole population....

 and survey sampling
Survey sampling
In statistics, survey sampling describes the process of selecting a sample of elements from a target population in order to conduct a survey.A survey may refer to many different types or techniques of observation, but in the context of survey sampling it most often involves a questionnaire used to...


Selecting samples

Survey samples can be broadly divided into two types: probability samples and non-probability samples
Nonprobability sampling
Sampling is the use of a subset of the population to represent the whole population. Probability sampling, or random sampling, is a sampling technique in which the probability of getting any particular sample may be calculated. Nonprobability sampling does not meet this criterion and should be...

. Stratified sampling
Stratified sampling
In statistics, stratified sampling is a method of sampling from a population.In statistical surveys, when subpopulations within an overall population vary, it is advantageous to sample each subpopulation independently. Stratification is the process of dividing members of the population into...

 is a method of probability sampling such that sub-populations within an overall population are identified and included in the sample selected in a balanced way.

Modes of data collection

There are several ways of administering a survey. The choice between administration modes is influenced by several factors, including 1) costs, 2) coverage of the target population, 3) flexibility of asking questions, 4) respondents' willingness to participate and 5) response accuracy. Different methods create mode effect
Mode effect
Mode effect is a broad term referring to a phenomenon where a particular survey administration mode causes different data to be collected. For example, when asking a question using two different modes , responses to one mode may be significantly different to responses given in the other mode...

s that change how respondents answer, and different methods have different advantages. The most common modes of administration can be summarized as:
  • Telephone
  • Mail (post)
  • Online surveys
  • Personal in-home surveys
  • Personal mall or street intercept survey
  • Hybrids of the above.

How to write good survey questions

Rules for writing good questions are given in classical survey books. A summary of these rules was made by Ten Brink (1992).
  • Rule 1. Use correct spelling, punctuation and grammar style .
  • Rule 2. Use specific questions. For example, "did you read a newspaper yesterday?", instead of "did you read a newspaper?".
  • Rule 3. Use a short introduction to question of behaviors. In this way you cannot only refresh the memory of the respondent, but also explain what you mean with the concept you are using. For example, with wines, you may not only mean red or white wine, but liqueurs, cordials, sherries, tables wines and sparkling wines.
  • Rule 4. Avoid the use of technical terms and jargon. An exception to this rule are questions that are made for a specific group of respondents, who regularly use jargon, e.g., doctors, lawyers and researchers.
  • Rule 5. Avoid questions that do not have a single answer. For example, "do you like to walk and ride to school?". Somebody who likes to walk, but does not like to cycle, cannot answer this question in the right way.
  • Rule 6. Avoid negative phrasing, e.g., "should the school not be improved?". This can lead to confusion and cost more effort to answer the question correctly.
  • Rule 7. Avoid words and expressions with multiple-meanings, like any and just.
  • Rule 8. Avoid stereotyping, offensive and emotionally loaded language. See also research ethics
    Research ethics
    Research ethics involves the application of fundamental ethical principles to a variety of topics involving scientific research. These include the design and implementation of research involving human experimentation, animal experimentation, various aspects of academic scandal, including scientific...

Response formats

Usually, a survey consists of a number of questions that the respondent has to answer in a set format. A distinction is made between open-ended and closed-ended questions. An open-ended question asks the respondent to formulate his own answer, whereas a closed-ended question has the respondent pick an answer from a given number of options. The response options for a closed-ended question should be exhaustive and mutually exclusive. Four types of response scales for closed-ended questions are distinguished:
  • Dichotomous, where the respondent has two options
  • Nominal-polytomous, where the respondent has more than two unordered options
  • Ordinal-polytomous, where the respondent has more than two ordered options
  • (bounded)Continuous, where the respondent is presented with a continuous scale

A respondent's answer to an open-ended question can be coded into a response scale afterwards, or analysed using more qualitative methods.


  • As in sample study few units are to be examined detailed study of the survey can be done.
  • As few units are to be examined the survey work requires less time. Thus in this way sample survey saves time.
  • As few units are to be examined the survey work requires less money. Thus in this way sample survey saves lots of money.
  • In sample survey few persons are required for the survey work so experts can be appointed for the survey. This will increase the reliability of the survey results.
  • When the test is of destructive nature, sampling is only the way out. In such cases the population survey is not possible.
  • A large area can be covered under survey in the available time and money.
  • If proper method is employed under the survey the results obtained will represent the population adequately. Surveys are relatively inexpensive (especially self-administered surveys).
  • Surveys are useful in describing the characteristics of a large population. No other method of observation can provide this general capability.
  • They can be administered from remote locations using mail, email or telephone.
  • Consequently, very large samples are feasible, making the results statistically significant even when analyzing multiple variables.
  • Many questions can be asked about a given topic giving considerable flexibility to the analysis.
  • Sample survey make measurement more precise by enforcing uniform definitions upon the participants.
  • Sample survey means that similar data can be collected from groups then interpreted comparatively (between-group study).
  • Sample survey is also used to check the accuracy of the census data (population survey).
  • Surveys are an efficient way of collecting information from a large number of respondents. Very large samplings are possible. Statistical techniques can be used to determine validity, reliability, and statistical significance.
  • Surveys are flexible in the sense that a wide range of information can be collected. They can be used to study attitudes, values, beliefs, and past behaviors.
  • Because they are standardized, they are relatively free from several types of errors.
  • They are relatively easy to administer.
  • There is an economy in data collection due to the focus provided by standardized questions. Only questions of interest to the researcher are asked, recorded, codified, and analyzed. Time and money is not spent on tangential questions.
  • Sample surveys are usually cheaper to conduct than a full census.


  • They depend on subjects' motivation, honesty, memory, and ability to respond. Subjects may not be aware of their reasons for any given action. They may have forgotten their reasons. They may not be motivated to give accurate answers; in fact, they may be motivated to give answers that present themselves in a favorable light.
  • Structured surveys, particularly those with closed ended questions, may have low validity when researching affective variables.
  • Although the individuals chosen to participate in surveys are often randomly sampled, errors due to nonresponse may exist (see also chapter 13 of Adér et al. (2008) for more information on how to deal with nonresponsonders and biased data) . That is, people who choose to respond on the survey may be different from those who do not respond, thus biasing the estimates. For example, polls or surveys that are conducted by calling a random sample of publicly available telephone numbers will not include the responses of people with unlisted telephone numbers, mobile (cell) phone numbers, people who are unable to answer the phone (e.g., because they normally sleep during the time of day the survey is conducted, because they are at work, etc.), people who do not answer calls from unknown or unfamiliar telephone numbers. Likewise, such a survey will include a disproportionate number of respondents who have traditional, land-line telephone service with listed phone numbers, and people who stay home much of the day and are much more likely to be available to participate in the survey (e.g., people who are unemployed, disabled, elderly, etc.).
  • Survey question answer-choices could lead to vague data sets because at times they are relative only to a personal abstract notion concerning "strength of choice". For instance the choice "moderately agree" may mean different things to different subjects, and to anyone interpreting the data for correlation. Even yes or no answers are problematic because subjects may for instance put "no" if the choice "only once" is not available.

Nonresponse reduction

The following ways have been recommended for reducing nonresponse in telephone and face-to-face surveys:
  • Advance letter. A short letter is sent in advance to inform the sampled respondents about the upcoming survey. The style of the letter should be personalized but not overdone. First, it announces that a phone call will be made/ or an interviewer wants to make an appointment to do the survey face-to-face. Second, the research topic will be described. Last, it allows both an expression of the surveyor's appreciation of cooperation and an opening to ask questions on the survey.
  • Training. The interviewers are thoroughly trained in how to ask respondents questions, how to work with computers and making schedules for callbacks to respondents who were not reached.
  • Short introduction. The interviewer should always start with a short instruction about him or herself. She/he should give her name, the institute she is working for, the length of the interview and goal of the interview. Also it can be useful to make clear that you are not selling anything: this has been shown to lead led to a slightly higher responding rate.
  • Respondent-friendly survey questionnaire. The questions asked must be clear, non-offensive and easy to respond to for the subjects under study.

Other methods to increase response rates

  • brevity – single page if possible
  • financial incentives
    • paid in advance
    • paid at completion
  • non-monetary incentives
    • commodity giveaways (pens, notepads)
    • entry into a lottery, draw or contest
    • discount coupons
    • promise of contribution to charity
  • preliminary notification
  • foot-in-the-door techniques – start with a small inconsequential request
  • personalization of the request – address specific individuals
  • follow-up requests – multiple requests
  • emotional appeals
  • bids for sympathy
  • convince respondent that they can make a difference
  • guarantee anonymity
  • legal compulsion (certain government-run surveys)

See also

  • Data Documentation Initiative
    Data Documentation Initiative
    The Data Documentation Initiative is an international project to create a standard for information describing statistical and social science data. Begun in 1995, the effort brings together data professionals from around the world to develop the standard. The DDI specification, written in XML,...

  • Enterprise feedback management
    Enterprise Feedback Management
    Enterprise feedback management is a system of processes and software that enables organizations to centrally manage deployment of surveys while dispersing authoring and analysis throughout an organization...

  • National accounts
    National accounts
    National accounts or national account systems are the implementation of complete and consistent accounting techniques for measuring the economic activity of a nation. These include detailed underlying measures that rely on double-entry accounting...

  • Official statistics
    Official statistics
    Official statistics are statistics published by government agencies or other public bodies such as international organizations. They provide quantitative or qualitative information on all major areas of citizens' lives, such as economic and social development, living conditions, health, education,...

  • Opinion poll
    Opinion poll
    An opinion poll, sometimes simply referred to as a poll is a survey of public opinion from a particular sample. Opinion polls are usually designed to represent the opinions of a population by conducting a series of questions and then extrapolating generalities in ratio or within confidence...

  • Paid survey
    Paid survey
    A paid or incentivized survey is a type of statistical survey where the participants/members are rewarded through an incentive program, generally entry into a sweepstakes program or a small cash reward, for completing one or more surveys.- Details :...

  • Quantitative marketing research
    Quantitative marketing research
    Quantitative marketing research is the application of quantitative research techniques to the field of marketing. It has roots in both the positivist view of the world, and the modern marketing viewpoint that marketing is an interactive process in which both the buyer and seller reach a satisfying...

  • Questionnaire construction
    Questionnaire construction
    A questionnaire is a series of questions asked to individuals to obtain statistically useful information about a given topic. When properly constructed and responsibly administered, questionnaires become a vital instrument by which statements can be made about specific groups or people or entire...

  • Social research
    Social research
    Social research refers to research conducted by social scientists. Social research methods may be divided into two broad categories:* Quantitative designs approach social phenomena through quantifiable evidence, and often rely on statistical analysis of many cases to create valid and reliable...

Further reading

  • Leung, Wai-Ching (2001) "Conducting a Survey", in Student BMJ
    Student BMJ
    Student BMJ is a monthly, international medical journal for medical students and junior doctors. It is published by the BMJ Group, which publishes the highly prestigious BMJ and over 30 other speciality journals....

    , (British Medical Journal
    British Medical Journal
    BMJ is a partially open-access peer-reviewed medical journal. Originally called the British Medical Journal, the title was officially shortened to BMJ in 1988. The journal is published by the BMJ Group, a wholly owned subsidiary of the British Medical Association...

    , Student Edition), May 2001

External links

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