I have seen some posts over the weekend discussing critical hits and whether they are effective compared to an increase in base damage. That caused me to look once more at character and skill screens and, to realise that there seems to be a number of views expressed, that seem to disagree as to how critical attacks work; hence this question.

How do critical attacks work in this game?

I can see how the chance of a critical hit is worked out as a percentage, but cannot see how the additional damage is worked out. The Critical Hit Strength is shown on the character sheet as an actual number, not as a percentage. This would seem to contradict the assumptions made that the damage of a critical hit is, for example an increase based on percentage, such as x1.5 or 150%.
However, if this critical hit strength is a value that is added to the base damage calculation then again, that seems to be peculiar, for example if you have a critical hit strength of +25 and, your attack base damage is 50 then that is a 50% increase; but if the attack base damage is 100 then the increase is only 25% (weaker weapons would get a greater boost).
Also if effective critical attacks do require investment in both of these 2 separate aspects and, the damage dealt is as low as some seem to argue, it does seem that those skills and perks that give a flat increase base damage are so efficient, that developing critical attacks are a waste of time; something in itself that does unlikely.

Whilst the views of any are welcome, perhaps a quick explanation from an official source would be particularly helpful.

Many thanks and cheers :)