The most basic form of forced choice surveys is the dichotomous questionnaire. In this form of survey the participant must choose between one of two polar extremes. A psychologist researching attitudes on sex may ask "have you ever viewed pornography?" or a representative of an insurance company may ask "have you ever smoked cigarettes?" In both these instances the participant must answer either "yes" or "no."
Another common form of forced choice surveys are Likert scales. These surveys, developed by Rensis Likert, are the most common types of questionnaires and can be extremely useful for all sorts of research. In a Likert survey, the participant must respond to a question by selecting one of an odd number of options (usually five or seven) along a spectrum. For instance, when you are leaving a restaurant, the manager may have you fill out a Likert asking whether you found the service, food and atmosphere "very good," "good," "neutral," "poor" or "very poor." These surveys offer the researchers more nuanced information while remaining quantifiable.
Rank order scaling, as the name suggests, involves a participant ordering items of a list according to one's preference. An example may be an auto company presenting a list of sports cars and asking participants to order them by how much a potential customer would want to own one. This forces participants to not only choose a favourite and non-favourite but also provides gradations of quality for the researcher.
The Guttman Scale, named after Louis Guttman, is a unique survey that is seldom used outside academic research. For this survey, the participant must provide a binary answer on an issue to increasingly extreme questions. A study on criminal attitudes may first ask, "I would not mind working with an ex-convict," followed by, "I would not mind having an ex-convict as a neighbour," followed by, "I would not mind my child dating an ex-convict," and so on to greater and greater extremes. The further along the participant provides positive answers, the stronger he or she feels toward the issue. This type of survey allows researchers to force a concrete yes-no answer from participants while also allowing them to place results on a variable scale.
Most surveys aim to force a definitive choice out of participants. This way, researchers are able to make meaning out of data conveniently and scientifically, rather than combing through endless open-ended responses. There are many forms of forced choice surveys and different ways of placing information on a scale. But it is most important to note that most serious surveys will force participants to chose one of a finite number of options.