A filtering question in a research questionnaire is designed to specifically target a segment of the study population and direct them to specific sections of the questionnaire based on their answer. For example, if the answer is “yes,” the respondent is directed to question 6, while if they answer “no,” they are directed to question 9 (in the case of a paper questionnaire). For online or telephone-administered questionnaires, the next question is automatically determined based on the filtering question. For example, in cases where the answers to filtering questions determine whether questions about application processing should be displayed, if “no” is selected, questions about processing times and quality will not be presented.

Filtering questions can also be useful in recruitment to decide whether an individual should be included in the sample based on their profile or the specific category sought for quota sampling. Thus, during a telephone survey or poll, if the screening question indicates that the respondent does not match the desired profile, the interview may be interrupted. It is important not to confuse the screening question with another selection method. For example, in the ONE study on press readership, an example of a screening question would be: [insert example of screening question].