6. Developing a Survey Instrument
A survey instrument is a tool for consistently implementing a scientific protocol for obtaining data from respondents. For most social and behavioral surveys, the instrument involves a questionnaire that provides a script for presenting a standard set of questions and response options. The survey instrument includes questions that address specific study objectives and may also be used to collect demographic information for calculating survey weights. In some surveys, questionnaire responses are augmented by other kinds of measurements derived from instruments, such as lab samples or physical assessments.
A difficult task in creating a questionnaire is translating a researcher’s questions into items that are sufficiently succinct and simple for the respondent to understand and provide accurate answers.
In general, survey questions should:
- Contain only one idea or question
- Define the scope to consider, such as the time period or activities that are relevant to the question
- Be written with neutral language to avoid leading the respondent to a specific answer
- Use language that enables less educated persons to easily understand the question.
- Contain response options that are simple, clear, consistent, and include the full range of responses that might occur
- For categorical responses, be mutually exclusive and exhaustive so that a respondent can pick one and only one option
- For numeric responses, guide the respondent to provide the response in a consistent format and units
Methodologies used to formulate good questions rely on cognitive psychology principles that express how humans process information. For example, because cognitive errors can be made recalling past events (recall error is a form of measurement error), dietary surveys ask each respondent to describe dietary intake for a recent, short time period such as the prior day. For some health and social science topics, standardized question sets are available that provide consistency across studies for specific measures. For example, a standard question set has been developed for evaluating a household’s risk of food insecurity or hunger.