Scale and Score
| The concepts scale and score are often confused, as they are closely related. The distinction between these two concepts is highlighted within this Wiki. However, one may often find them used interchangeably in other resources on health measurement scales, thus giving rise to confusion. |
Scale
- In this Wiki, scales are defined as formulae or algorithms used to generate a measurement for estimating a particular construct..
- An example of a scale is the Framingham cardiovascular risk scale.
Score
- Scores are the estimates generated by a scale as defined above.
- An example of a score is a percentage risk prediction generated by the Framingham cardiovascular risk scale.
Validity
- Strictly speaking, validity does not apply to a specific scale but rather, the scores that are generated by that scale on applying it to a particular group of people and in a certain context.
- Score validity is the extent to which the estimates forthcoming from a scale (e.g. probabilities for each patient that they will have a cardiovascular event within 10 years) reflect the observed data available for the construct which that scale represents (in this case, whether individual patients go on to experience a cardiovascular event within 10 years). It can be assessed by means of calibration and discrimination statistics.