Unintended consequences  

The Bloviator (whose permalinks aren't working) has some observations about the tradeoffs between voluntary and involuntary quarantine:

Obviously, for purposes of maintaining the proper balance of human rights/dignity and public health protection, a voluntary approach is recommended. And while there are risks to this approach, as evidenced in the above case, the mandatory quarantine approach offers even more significant risks, like those who may be infected being reluctant to come forward and/or seek diagnosis and treatment for fear of being stigmatized and/or locked away.

I can't find any reference to whether quarantines in Hong Kong or China are volunatary, and I'm not sure it's safe to assume that they aren't, even in the case of the latter. I have a feeling we're never going to see any reliable/straightforward information about the initial spread of the disease in China, but if they are using involuntary quarantine, it might be illuminating to compare how the different policies affect contagion levels.