How to quantify U-Pb discordance?

In a new Geochronology paper, Vermeesch (2021) shows that the current practice of filtering discordant U–Pb data based on the relative difference between the 206Pb/238U and 207Pb/206Pb ages is just one of several possible approaches to the problem and demonstrably not the best one. An alternative approach is to define discordance in terms of isotopic composition, as a log ratio distance between the measurement and the concordia line. Application to real data indicates that this reduces the positive bias of filtered age spectra.

Vermeesch, P., 2021. On the treatment of discordant detrital zircon U-Pb data, Geochronology, 3, 247-257, 2021.