It's been some considerable time since we last updated the way that scores are calculated.  As this affects your ability to compare your site over time and how you stand in any of our surveys that your site might be part of, it is not something we would consider doing on a regular basis.

However with the launch of the new interface, much of which was based on your invaluable feedback, observations and requests, we have also - again based on your feedback - changed some aspects of the scoring.  This might come from the reclassification of an error - such as some email errors (that have moved from being a failure to a warning) or failing cookies on external pages (which are no longer checked) - which will affect your scores.  More information about what tests have changed or been reclassified is here http://blog.sitemorse.com/2009/01/some-tests-have-moved-between.html

We have also improved the assessment of the download speed by changing the calculation to make it better reflect the download speed of your site (see blog posting on this change here http://blog.sitemorse.com/2009/01/updated-download-speed-calcula.html  This meant that the benchmarks for the download speed had to be updated to reflect this change.

To see how the scores are now calculated click here http://www.sitemorse.com/benchmark.html

These changes will make the scores more accurately reflect how well your site is doing and tie the score more closely to the actual impact on your customers.  This will help you focus on the priority issues. 

These changes are going to affect different sites in different ways and so the survey tables, starting from January's edition, may well see significant changes.  This is inevitable whenever changes are made.  Which is why we don't do it often and why we've done it starting with the January surveys so it will be easy to remember when the changes took effect when looking back over several surveys.

If you'd like to discuss this in more detail please feel free to contact me gevans@sitemorse.com