Reliability & Validity

Reliability & Validity

1. extent to which a measurement instrument (e.g. tool, test or questionnaire) is dependable, stable and consistent when repeated under identical conditions.

2. refers to the ability of the scale to provide consistent, stable information across time and across respondents.

3. about the consistency and trustworthiness of research findings and it is often considered in relation to the issue of whether a finding is reproducible

4. reliability of a specific scale or measurement tool/instrument is assessed statistically

5. enhanced by a range of measures that are set out in the study protocol

   • Training
   • Calibration
   • Monitoring and conducting tests
     • test at different times or by different researchers

6. extent to which an instrument or scale (e.g. laboratory test, questionnaire) measures what it is supposed to measure (e.g. do IQ tests validly measure the construct of IQ?).

7. most published research where an instrument is used, the researchers usually compare their instrument with a 'gold standard' measure.

8. maintained in quantitative research when studies are conducted using the strict rules and standards appropriate for the study design and the measurement instruments.

9. rules of quantitative validity should NOT be applied to qualitative research.

10. not inherent to the measurement tool or instrument but should be evaluated within the context of how the test or instrument is to be used and the specific population from which the study sample has been drawn.

    • evidence for the tool's validity is not quickly or easily assessed but is gathered over time

11. Responsiveness

    • ability of the instrument to measure change following an intervention over time.

12. Types

    • Content
    • Face
    • Construct
    • Criterion
    • Concurrent
    • Predictive