A question of size

I've read various articles recently regarding "vanity sizing"...or the variance of measurements in clothes which are labelled the same size...presumably to make everyone think "gosh, I've lost a lot of weight". I was curious so I decided to do a completely non-scientific study of some vintage 80's skirts from my closet compared to Banana Republic's online size chart (as I said non-scientific). Our contestants?

1) Moschino "Liechtenstein" skirt - labelled a 48 (US 14)...waist measurement 32" 2) Moschino striped skirt - labelled a 46 (US 12)...waist measurement 30" 3) Roser Marce gingham tulip skirt - labelled a 40 (US 10)...waist measurement 28" And the results? In two of the cases, the modern sizes are larger. Banana Republic's size 10 comes in with a waist measurement of 29" and their size 12 measures 30.5" (only the 14 is identical at 32"). Not a huge numerical difference but how much additional weight overall are we carrying around to equal that extra inch in the waist?