Payables turnover

CFAI text and Schweser seem to differ on this ratio: CFAI book3 pg 584 => payables turnover = purchases/avg. payables Schweser => payables turnover = COGS/avg. payables Which one is correct?

What Schweser does is not wrong. But it’s more accurate to divide average payables into purchases. that equals COGS plus the increase of inventory over the year.

righto, thanks