The survey technique involves the collection of primary data about subjects, usually by selecting a representative sample of the population or universe under study, through the use of a questionnaire. It is a very popular since many different types of information can be collected, including attitudinal, motivational, behavioural and perceptive aspects. It allows for standardization and uniformity both in the questions asked and in the method of approaching subjects, making it far easier to compare and contrast answers by respondent group. It also ensures higher reliability than some other techniques.
If properly designed and implemented, surveys can be an efficient and accurate means of determining information about a given population. Results can be provided relatively quickly, and depending on the sample size and methodology chosen, they are relatively inexpensive. However, surveys also have a number of disadvantages, which must be considered by the researcher in determining the appropriate data collection technique.
Since in any survey, the respondent knows that s/he is being studied, the information provided may not be valid insofar as the respondent may wish to impress (e.g. by attributing him/herself a higher income or education level) or please (e.g. researcher by providing the kind of response s/he believes the researcher is looking for) the researcher. This is known as response error or bias.
The willingness or ability to reply can also pose a problem. Perhaps the information is considered sensitive or intrusive (e.g. information about income or sexual preference) leading to a high rate of refusal. Or perhaps the question is so specific that the respondent is unable to answer, even though willing (e.g. "How many times during the past month have you thought about a potential vacation destination?") If the people who refuse are indeed in some way different from those who do not, this is knows as a non-response error or bias.Careful wording of the questions can help overcome some of these problems.
The interviewer can (inadvertently) influence the response elicited through comments made or by stressing certain words in the question itself. In interview surveys, the interviewer can also introduce bias through facial expressions, body language or even the clothing that is worn. This is knows as interviewer error or bias.
Another consideration is response rate. Depending on the method chosen, the length of the questionnaire, the type and/or motivation of the respondent, the type of questions and/or subject matter, the time of day or place, and whether respondents were informed to expect the survey or offered an incentive can all influence the response rate obtained. Proper questionnaire design and question wording can help increase response rate.
There are three basic types of surveys: