Effect of the present-day neutron lifetime on the preferred value of α for unification, dilaton, and clocks cases (top, middle, and bottom panels, respectively). In the clocks case, the parameters R and S were marginalised. Left and right panels correspond to the cases without and with the experimental prior on the neutron lifetime discussed in the text; the one-sigma range corresponding to this prior is also shown for illustration purposes. It is important to notice that for each model the vertical axis is the same in both cases, while the horizontal one is not. The 68.3, 95.4, and 99.7 percent confidence levels are plotted throughout.