Scanning for Lower Percent Change from 252 Day High

You can use the max( ) function to the find the highest value of something over the period you specify - so for instance, 252 day high is max(252, high) or max(252, close), depending on which you want to use. For the lowest value over some period, you would min( ).

To find a per cent of anything, like the max( ) value, multiply by the decimal equivalent of the percent. The decimal equivalent of 100% is 1.0. Something less than 100% would be something less than 1.0 - in your case, .8. If you wanted 20% above something - like an MA - it would something more than 1.0 - say 1.2

max( ) * .8