Reliability and validity

• Reliability

  Consistency. If you can repeat a measurement and get the same results, then the measurement is reliable
• Qualitative methods 


  Less reliable. Unstructured interviews and case studies are difficult to repeat in the same way
• Validity


  Whether a result reflects 'real-world' behaviour
• Sampling methods


  Not always true validity
• Experimental designs


  Not always reflect real life
• Qualitative methods


  Qualitative methods have greater validity as they provide unrestricted information

  Qualitative data depends on subjective interpretation, reducing the validity if conclusions