Reliability, validity, generalizability
and credibility.
Shipman’s 4 key questions about the quality of research
RELIABILITY
If the investigation had been carried out again by different researchers using the same methods,
would the same results have been obtained?
Subject error (different results on different days) Subject bias (try to please researcher) Observer
error and bias.
VALIDITY
Question 2. Does the evidence reflect the reality under investigation? Has the researcher found out
what he/she thinks or claims it’s about?
Posible threats to internal validity.
1. History.
2. Testing
3. Instrumentation.
4. Regression.
GENERALIZABILITY
Selection (specifici to group) Setting (specific to setting) History (particular past experience)
Construct effects. (only this group has these constructs)
CREDIBILITY.
Question 4. Is there suficiente detail on the way the evidence was produced for the credibility of the
research to be assessed?