So I read the Google multi screen doc and how it automagically scales based upon what looks like a resolution value of 160.

So if I am creating an image for an icon in Photoshop for an mdpi screen, would it be correct to set the resolution to 160 and the width and hight to 48X48.

or

Would you set resolution to 72 and then just set the width and height to 48 X 48?

Thanks in advanced for resolving my confusion?