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!
When I traded full time, I looked at the diff in IVol between the 25 Delta call and the 25 Delta put. I also found it showed changes short term supply/demand.
I have a range of preferred trade deltas and track them with (traffic-light) color formatting. I compute P(HIT) probabilities separately, but format them in a similar-but-not-identical fashion. (This is Gaussian/Normal, and thus symmetric.) With this method, I can see the differences, by side, by strike, and by expiry, between symmetric and the market's bias-of-the-moment, in an instant. If I track them to the (individual strike) IV, that is discernible as well, and thus is skew, and at a glance. Very handy is fast moving markets.