known systems. The authors found that for the second phase of mass loss, a CE event with $\alpha_\mathrm{CE} \lambda\simeq 2$ could be fit to the majority of observed systems. However, one should assess the implications of this with caution as we would expect use of a single-valued parameter to be inappropriate in the general case, as there is little reason to assume that such a parameter should not vary under differing conditions. Specifically, in the case of the $\alpha_\mathrm{CE} \lambda$ formalism, $\lambda$ is known to vary along the giant branch, and it would seem a somewhat awkward contrivance to suggest a single envelope removal efficiency is shared among all binaries undergoing a CE. Such considerations are essential in order to provide more substantive results in population synthesis. [@Nelemans00] find plausible values for $\alpha_\mathrm{CE} \lambda$ ranging from 0.5 to 3 for different observed cases. We take a value of $\alpha_\mathrm{CE}$ to be reasonable so long as it is in the physically meaningful range between $0$ and $1$.

The same reconstruction analysis in [@Nelemans00] has also shown that the first phase of mass loss can be explained with a CE only if $-15 \leq \alpha_\mathrm{CE}\lambda \leq -5$, well outside any physically acceptable 