doi: http://dx.doi.org/10.1017/S0007123414000441, Published by Cambridge University Press, 17 November 2014

The authors apologise for the insertion of Figure 3 in their article. It is mistaken, and does not appropriately summarise the Figures in Appendix B.

New paragraph to be inserted at the bottom of pg 12 (also going on to pg 13)

If we introduce length as an additional variable, the correct way of thinking is to consider amendment frequency and constitutional rigidity together, because amendment procedures are engaged despite the fact that the constitution is “locked.”Footnote ¹ One might expect that the sum of amendment frequency and constitutional rigidity is more or less the same for different constitutional lengths, since one compensates for the other. Yet, Figure 3 shows a different picture, one of a very strong and significant positive relationship between length and the combination of constitutional rigidity and amendment frequency. We produced this figure by normalizing the two variables presented in Appendix B, to account for differences in scale in each of the two variables (both variables are positively related to length, but we wanted to ensure that one would not have higher significance than the other because of the units of measurement). As long as amendment frequency is highly dependent on length, even mildly negative slopes of constitutional rigidity (for another sample of countries, or with a different indicator of rigidity) would produce the same result. Later, we present a more rigorous explanation for this relationship.

Paragraph to be removed from pg 12-13

In this case, not only do the data from the OECD contradict our expectations from Figure 1; the expectation of negative slope is also contradicted by the data, but in a much more pronounced way. Now the relationship in Figure 3 is clearly positive and highly significant (at the 0.001 level). Given our expectation of a negative slope, Figure 3 is even more puzzling. It demonstrates that longer constitutions are both more rigid and more frequently amended than shorter ones. Before proceeding, it is worth presenting two brief case studies to show that Figure 3 is not simply a statistical artifact but in fact reflects the experiences of OECD countries (notice that even the United States is not a noticeable outlier in Figure 3).Footnote ² Later, we present a more rigorous explanation for this relationship.

Figure to be inserted, replacing Figure 3 (pg 38):

Fig. 3 Constitutional rigidity and number of amendment events in OECD vs. log constitutional length