Holger Spamann, Are Sleepy Punishers Really Harsh Punishers? Comment on Cho, Barnes, and Guanara (2017), 29 Psychol. Sci. 1006 (2018).
Abstract: Cho, Barnes, and Guanara (2017) analyzed criminal sentencing by U.S. federal judges in the years 1992 through 2003. Controlling for case covariates, they estimated that “sentences rendered on sleepy Mondays”—Mondays immediately following the start of daylight saving time, when the night from Saturday to Sunday is shortened by 1 hr—“were approximately 5% longer than those rendered on [the immediately preceding and subsequent] Mondays” (p. 243). Cho et al. estimated that so large a difference would arise by chance with a probability of only 0.5% if judges tended to render equal sentences on those three Mondays (i.e., p = .005). Cho et al. interpreted this finding as evidence that sleep-deprived judges punish more harshly than judges who have not been sleep deprived. This Commentary raises three concerns about Cho et al.’s analysis and conclusions. First, Cho et al. reported results from a model that differed from the model described in their article. The latter model is theoretically superior but yields a nonsignificant result. Second, even the model used by Cho et al. yields a much smaller, nonsignificant coefficient if one accounts for judges’ choice whether to impose any prison time at all, as is standard in the sentencing literature. Third, new data from 2004 through 2016 show not even a trace of a sleepy-Monday effect. Table 1 summarizes all four models mentioned thus far (Models 1, 2, 4, and 7) along with several models providing robustness checks (Models 3, 5, 6, and 8), and the remainder of this Commentary discusses these eight models in more detail. At the outset, it is worth noting that Cho et al.’s result depends entirely on their model: As reported in their note 3, a model without their control variables did not yield a statistically significant estimate of a sleepy-Monday effect.