Whether there are techniques is irrelevant, whether people trust that they'll not face consequences due to their answer is much more important. You can reassure them as much as you want - who really would want to risk real-world consequences for a random survey?

Alternatively there might be somewhere in the fine print how Chinese participants were invited/selected - it wouldn't be the first such data where PRC manages to manipulate the sampled group to get a positive result (see eg PISA).

> who really would want to risk real-world consequences for a random survey?

Why not? We don't know the baseline behavior and expectations of the respondents.

I think we differ on where our subjective Bayesian priors are situated.

I'm more at the 50/50 mark in that I think the results could be biased but at the same time, there's no necessity that they must be. Whereas most people on this thread automatically assume a priori that the survey results surely are biased, because China.

>I can only imagine Ipsos, being a survey firm, would have used some of these techniques.

You're giving them too much credit. Unless this was explicitly mentioned in the methodology (there's a methodology section at the end, and it's not there), I'm going to assume that the questions were directly asked.