EV/EBITDA valuation

Hi there,

I’ve came across some method of adjsuting EV/EBITDA multiple for comparable companies group when valuing target company.

EV adjustment = (size premium / country risk premium) x (tax shield adjustment) x (capital structure adjustment)

Adjusted EV/EBITDA = Raw EV/EBITDA / (1 + Raw EV/EBITDA * EV adjustment)

Do someone know this method and especially why there are adjustment for tax shield and capital structure when EV/EBITDA should be neutral to this things? To be honest I see this first time and no such method was mentioned in CFA materials.