GreedyStepWise threshold

Hi everybody,

I am new in data Mining and WEKA tools. I have some data and i would like to filter them before applying the Linear regression. I apply the GreedyStepWise filter to my attributes (82), but what i did not understand is how can i set the threshold? What is the range of this value? For example i tried Threshold = -0.7305 and i obtained 2 attributes from 82 after filtering.

Any help please ?

Thank you,
Najem