How to use isoutlier based in a part of the data?

I have a vector of datas. Like this,   a =[0;0.0028;0.0002;0.0039;0.0061].   As you see, since the 4° element, the values start growing more until the end.   I was trying to determine a threshold to define the 4° and 5° elements as ouliers using 'isoutlier' function from Matlab. I did it. But I had to define a fixed 'ThresholdFactor'value using one of the methods the function has.   I would like the 4° and 5° values to being identified as outliers. Not based with all the vector datas, but because they are bigger than the 1°, 2° and 3° elements. I mean, I would like to find the outliers based on the backforward datas [0;0.0028;0.0002].   The vector I posted is an example. The size must be generic.   Can you help me?   P.S. (Actualized): As I said, depending of the data entries, my vectors gonna have different sizes. But in all cases, the phenomenum they represent, makes the vector values would be bigger at the end.   I can't find a way to define when the datas gonna be outliers since the vector will not always be the same. I need to generalize. So what I really need is to identify when the values start growing until reach the end. For instance, for my example, it would happen from the 4° position.