Thank you for nabbing this from Sithwarrior.com. I'm having a horrible brain moment atm and I'm attempting to see how much 1 point of defense and 1 point of shield rating contribute to their percentages and how many points it takes to get 1% of said rating.

If my defense has 19 points and grants an additional 1.38% then does each point contribute 0.07263%, and 13.xx points gives roughly 1% defense rating?

It's not that simple. For one thing it matters what level you are. Also, all ratings have diminishing returns so you can't calculate it's value accurately per point: each point is worth less than the one before it.

People discussing tanking at sithwarrior.com are saying that defense is stronger than shield or absorption, but you can't stack one stat too heavily because of the diminishing returns.