The other thing is that suicides are non-Poissonian -- they occur somewhat more clumpily in time than you'd expect from pure randomness. A high-profile suicide tends to inspire other borderline-suicidal people to go through with it. A high-profile rash of suicides, then, could really gain some momentum.

If suicides at the factory are getting a lot of attention then they're right to act against it even if it isn't a higher-than-usual rate.