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Validity is the extent to which an instrument, a survey, measures what it is supposed to measure: validity is an assessment of its accuracy.

Often it is desirable to use more than one to facilitate a more rounded judgement of validity. These are assessed by considering the survey’s reliability and validity.įollowing on from our previous blog which looked at approaches to assessing reliability, this blog focusses on ways to assess a survey’s validity.Īs with reliability, the validity of a survey can be assessed in a number of different ways and the methods to choose will depend on the survey design and purpose. Reliability and validityĪs with scientific measurement instruments, two important qualities of surveys are consistency and accuracy. The responses to these individual but related questions can then be combined to form a score or scale measure along a continuum. They are better measured by asking a series of related questions covering different aspects of the construct of interest. They are used frequently in social science to measure what psychologists call constructs.Īs constructs are intangible and complex human behaviours or characteristics, they are not well measured by any single question. While scientific measurement instruments measure physical properties like velocity or weight, questionnaire surveys often measure respondents’ self-reported attitudes, opinions or behaviours. Questionnaire surveys are measurement instruments.