(roughness factors are seldom reported), so one should not expect any correlation in the plotted data. Vetter performed traditional Tafel analysis on various HER catalysts and demonstrated that while 𝛼 . ! was somewhat consistent across all tested catalysts, the log '" (𝑖 ",. ! ) varied across these catalysts varied by many orders of magnitude and were uncorrelated with 𝛼 . ! . 9,46 Therefore, the apparent correlation between the fit 𝛼 $ and log '" (𝑖 " ) is unexplained. We note that a correlation has been observed in thermal catalysis between the preexponential factor and the activation energy, and is referred to as the "compensation effect". Barrie has discussed the mathematical origins of this effect and its relationship to random experimental errors. In this connection, Bond et al. have proposed a set of guidelines to establish when the effect is physically meaningful. First, the dataset of must be sufficiently large; the range of transfer coefficients should be such that the largest value is at least 50% greater than the smallest. Second, the effects of the reaction order and bulk species concentration must be properly accounted for (Figure ). Lastly, we add that, for electrocatalysis, the effects of active surface area should be properly deconvoluted. For the data fit in this work, experiments were all reported based on geometric surface area of the cathode rather than the electrochemically active surface area (ECSA), making roughness effects difficult to deconvolute.