Differences in inferred WD formation time Δτ ≡ τ_BE − τ_SSE (see text) for WDs from binary mergers as a function of WD mass in our default model. Top: the colour logarithmically indicates the 2D PDF inferred from our data. Bottom: box plots of the Δτ within indicated mass bins. The blue and red lines indicate the mean and median values of the distribution, respectively. The black boxes represent the IQR, which is equal to the difference between the upper and lower quartiles of the distributions.