validity and reliability of research instrument

These external criteria can either be concurrent or predictive.Ĭoncurrent validity criteria are measured at the same time as the survey, either with questions embedded within the survey, or measures obtained from other sources. Face validity is often seen as the weakest form of validity, and it is usually desirable to establish that your survey has other forms of validity in addition to face and content validity.Ĭriterion validity is the extent to which the measures derived from the survey relate to other external criteria. A survey has content validity if, in the view of experts (for example, health professionals for patient surveys), the survey contains questions which cover all aspects of the construct being measured.įace and content validity are subjective opinions of non-experts and experts. A survey has face validity if, in the view of the respondents, the questions measure what they are intended to measure. How do we assess validity?įace validity and content validity are two forms of validity that are usually assessed qualitatively. 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.

Validity and reliability of research instrument