Levels of evidence are based on how high the internal validity is.
As a result high internal validity often comes at the cost of generalisability. The highest validity studies often are those looking at a specific intervention in ideal circumstances.
Evaluating the study methodology for sources of bias allows us to assess the study’s internal validity. In our session we asked two of our audience members to draw our head of service as a demonstration of the importance of reliability.Ī study’s internal validity reflects the author’s and reviewer’s confidence that bias has been minimised and eliminated. If James runs the race several times and each time a different person is timing him he’d want them to be measuring to the same accuracy. If James runs the race twice at the same speed he’d want the same outcome. There are many different types of reliability. So if James runs the Great North Run at the same speed he will get consistent times if the race is being measured reliably. On the other hand reliability describes whether the race and stopwatch themselves produce consistent results given similar conditions.
