What does the Quality Score mean?
This page tells you how the Quality Score is all about. If you want to find out more, follow the links in the text below.
How to Interpret the Score
When viewing a list of links, the Quality Score gives you our assessment of the quality of the information at the other end of the link. A high score tells you that the information is likely to be trustworthy.
(We should emphasise that this is an inherently subjective exercise, so you should regard our ratings as a guide rather than as a definitive value.)
Note that it's not an assessment of the quality of any treatment or test described by that information!
To find out why a particular page has been given its score, click the number and you’ll see a short summary of the page and comments on how we thought it could be improved. You’ll notice that we show Usability and Reliability separately on this page.
A Comparative Scale
For any rating scheme to be useful, it has to differentiate between different levels of quality. This is a real challenge, particularly at the upper end of the quality range, where we have to take into account what is known about how rigorous, evidence-based methods add to information quality. So, the difference between a 70% site and an 80% one may be much less than the difference between a 1-star site and 2-star one.
Our Assessment Tool
Our assessments are made using a checklist. Briefly, we score each web page on a set of questions about the usability and reliability of the information. The total score is converted into the percentage you see on the screen. What this means is that any page with 70% or higher is likely to have information that is both usable and reliable. Links with lower scores may be lacking in one of these aspects.
Who does the assessments?
The assessments are carried out by trained, experienced information professionals. When we tested the scoring system we found excellent agreement between different assessors' scores for the same information.