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Posted by sanjaysrivastava on 12 Mar 2013 at 01:39 GMT

I came across this article after a colleague forwarded it to me. While I find the subject matter quite interesting, I noticed several anomalies and had one general comment about the design:

1. For Studies 1, 2, and 3, the Ns reported in the abstract do not match those reported in the body of the paper.

2. For Study 2 the authors report the following: "In Study 2, those primed with science responded more severely to the moral transgression (i.e., condemned the act as more wrong; M = 95.95, SD = 4.37) relative to those in the control condition (M = 81.57, SD = 5.09), F(1, 31) = 4.58, p = .040." Two things need to be stated about this:

(2a) The 2 experimentally assigned groups are approximately 3 standard deviations apart (Cohen's d = 3.03, roughly corresponding to a Pearson's r of .83). That strikes me as highly improbable. For comparison, Cohen suggested that a d=0.80 should be interpreted as "large."

(2b) The F statistic (and its associated p-value) for this study does not correspond to the means, standard deviations, and sample size (neither the N stated in the abstract nor the N stated in the method section).

3. In Study 4 the authors write, "As predicted, those in the science condition allocated less money to themselves (M = 2.71, SD = 1.43) than those in the control condition (M = 2.84, SD = 1.11), t(41) = 2.06, p = .046." The t statistic and p-value reported do not match up to the means, standard deviations, and sample size. Assuming n=21 in one condition and n=22 in the other, I calculated t(41)=0.33, p=.74 from the reported means and SDs. In other words, one cannot reject the null hypothesis.

4. More generally, it strikes me that these sample sizes (even the larger of the ones reported) would afford relatively low power to detect a population effect of plausible magnitude. The probability of rejecting the null 4 times out of 4 studies would be even lower. For example, if the population effect is d=0.5 (a "medium" effect according to Cohen), a single study comparing 2 groups of n=25 each would have approximately 40% power to reject the null (alpha = .05, two-tailed). The probability of rejecting the null 4 times in a row, with 40% power in each study, would be 0.40^4, or about 2.6%.

No competing interests declared.

RE: Anomalies

christinema replied to sanjaysrivastava on 12 Mar 2013 at 03:06 GMT

We appreciate the catching of the discrepant N's reported in the abstract vs. main manuscript. We checked our data, and the N's reported in the main manuscript are correct' we apologize for our oversight in updating the N's reported in the abstract. With respect to Study 2, the values reported after the means are the standard errors, and not the standard deviations, and we again appreciate the catching of this misunderstanding; the standard deviations are 28.02 and 7.69 for the control and experimental conditions, respectively.

With respect to Study 4, we again double checked our data and while the results of the t-test are correct, the means/SDs should be corrected as follows: M = 3.04 (SD = 1.11) for the control and M = 2.24, SD = 1.43 for the experimental. The sample size is 43, as stated in the main text, and there were 26 participants in the control condition; 17 in the experimental.

No competing interests declared.

RE: Anomalies

skoleva replied to sanjaysrivastava on 24 Mar 2013 at 02:02 GMT

My concerns exactly Sanjay...

No competing interests declared.