Relative Stack.

Have you face a situation that you have 20BB but most of opponent has 40~50BB? Unlike most people's thought, This(or like this) situation happens very common, For example, If you lose 60~70% of your stack on early stage on general SnG, your stack would be dropped to 20~25BB, which is not considered "short stack". However, other opponents usually have 60~100BB. This means that your re-steal, squeeze and blind steal tool doesn't worked well compared to the situation that most player has 20~25BB. In other words, if you have far less stack than others, fold equity is dropped significantly.
Here is some examples
ex. 1 -- ex. 2
P1 = 80BB -- P1 = 20BB
p2 = 66BB -- P2 = 15BB
p3 = 73BB -- p3 = 21BB
p4 = 140BB -- p4 = 54BB
p5 = 53BB -- p5 = 17BB
p6 = 45BB -- p6 = 25BB
Hero(p7) = 18BB -- p7 = 18BB
p8 = 122BB -- p8 = 22BB
p9 = 70BB -- p9 = 20BB

Everyone folds to hero, playstyle between case 1 and case 2 is same. hero has QJs what should hero does?
Most people think that playstyle of case 1 and case 2 should be differ.

This cases represent the relative stack. both hero has 18BB. I call it "absolute middle stack"(15~22BB stack). However, In case 1. everyone has 50~140BB except hero. I usually call it "relative short stack" whereas in case 2. everyone has 15~25BB except p4 I usually call it "relative middle stack"

I think most good SnG players know this difference and reflect this fact and apply the strategy. However, I can't.. I don't know how to play when I'm "relative short stack" and "relative middle stack".. etc.. Many poker sites have a guide about "how to play when you reach (X)BB". however, I didn't find any guide about "how to play when you are short stack compared to others."

Any guide about how to play when I have short stack compared to others?"

No guides?... Sad.....

Your play doesn't change as much as you think. The biggest difference is that when you're a relative short stack you have to adjust for the lower fold equity - in other words, bluff less and be willing to go all in with more hands that you raise with.

In both cases that's an easy open from the button, the difference is that you're more likely to get flat called by the big stacks - at the shorter table they will be more likely to 3bet or fold.