We all know that laptop makers have been using misleading figures for battery life for years now. The packaging would say 10-12 hours, but when you started using the thing you wouldn’t get anything near that and Sony is fessing up.
Most venders use the Japanese tech association Jeita’s method, which is the average of power depletion when idle and playing a movie file. This seems pretty far from every day uses. Sony is going to switch to the Jeita “A” standard that only uses the movie file results. I still don’t know how accurate this will be, but it should be better than the other method.