% Complete vs Physical % Complete

Is there some way to make the % Complete field represent the Physical % Complete? That is to say for the % complete to only reflect the status in the work effort field regardless of the duration. 

For example:

IF Total Effort = 10 hours & Completed Effort = 5 hours (as would remaining effort)

THEN % Compete =50%

REGARDLESS of whether the duration says 3 months.

Currently the automated calculations always factor in the duration and it's not what I'm after.

Cheers