What are some industry/widely used methods/metrics to keep track of skew? Do you: Keep track of the differences in IV based on delta. For example 25d IV - 50d IV. Use a percentage based system. (25d IV)/(50d IV) Track slope plotting IV against moneyness. I'm reading this document and it has a bunch of graphs with IV on the y axis and ln(strike/spot)/(averageIV * sqrt(time)) on the x-axis. Thanks!