It turns out that several of the countries that had signaled their intention not to attend, sent representation anyway. This makes the relationship between press freedom and attendance at the ceremony even more striking than in my original analysis. In the graph below, the countries that had at some point announced their intention to remain absent are colored orange (Argentina, Colombia, Philippines, Serbia, and Ukraine). It is at least plausible that the foreign policy establishments in these countries miscalculated the pushback they would get from domestic media.
All of this does not mean that international pressure is irrelevant to the story. China can probably credibly threaten small punishments to most countries for attending but not big ones. So, the cost of attending may be pretty similar across states. There is much greater variation in the domestic cost for giving in to Chinese pressure. So, press freedom does a pretty good job in accounting for the variation in who attends and who does not. Yet, without China’s ability to credibly threaten repercussions, the whole thing would not have been an issue.
Update: Martin Edwards reports that several measures of China’s outward Foreign Direct Investment (FDI) are not significant correlates of the decision of attend and that Press Freedom remains a significant substantively strong predictor when measures of investment are included in a regression (his measures were FDI stock measured in current US dollars and exchange rates per capita, and FDI flows as a percentage of GDP).
Update2: This is Dan Drezner’s take. All I would add is that it is important not to confuse what a country could lose if China were to withdraw all its investment/trade with the credible repercussions for attending the ceremony. China has been willing to sanction in the past on these symbolic issues but ultimately remains pretty rational in where it invests or who it trades with.