A semi-empirical theory for global energy confinement in the stellaratorW7-AS is presented.It employs elementary rules of probability theory together with thetransformation properties of the basic equations describing plasmabehaviour.The semi-empirical theory allows model comparison between four differentkinetic plasma models.The analysis is applied to the 153 t ≈ 1/3 W7-AS data documented inthe international stellarator database.It is found that the collisional low-β kinetic model describes best the physics of W7-AS energy confinement.Finally, the predictive power of the semi-empirical theoryis successfully tested in the prediction of the energy content in (singlevariable) density and power scans performed in W7-AS.