Erratum

After the publication of this work [1], we became aware of errors in the reported results in Table 1. A corrected version of this table appears below. The main error involved reporting results for the low SEL class in the high SEL class row, and vice versa. Other small errors in reported p-values in the final column of the table have also been corrected.

Table 1 Summary statistics for daily percentage deviation from the long-run mean ATV (Δ t ) for various demographic groups
Full size table

The only implication of correcting these errors for the results discussed in the paper is to strengthen rejection of one of the null hypotheses tested. In the original text we observed that, “During the intervention period, on average the high SEL group shows a response that is over 50 % greater than that of the low SEL group.” Furthermore we remarked that, “This difference is significant at the 5 % level.” This difference is in fact significant at the 1 % level. We regret the error.