[SongofEarth]

It's important to note that most Chinese people hardly ever use email, the Internet started rather late in China, for most Chinese people the Internet means smartphone and WeChat, and WeChat often is the only place where business communication happens, had they put a WeChat QR code on the business card, the result would be much more interesting.

[pphysch]

Important cultural difference that the study failed to highlight.

You'd probably see a similar <15% success rate if you used a WeChat QR code for contact in the West. People might scan the code, but stop once they realize it's an unfamiliar platform that they don't have an account for.

[davetannenbaum]

It's a fair point, but we've tried to test this issue in a number of different ways. Based on the available data, cross country differences in email usage doesn't seem to have a meaningful impact on our results. See my comment above to gyf304.