My advisor commented that I need to fix my English, please help me find the English problem here.
The key indicator is an exploitable population. The more exploitable workers are the more likely they are being exploited. This means we need a way to measure each population’s exploitability. The second metric is the lack of violations. This is not an indicator of a lack of exploitation; a lack of known exploitation may be an indication that a domain may be running under-the-radar.
The second metric is the lack of violations.
I don't see an English error here though I am a native speaker and he is a native German speaker so he actually learned English at one point where as I just 'know it.'
The comment was made with a sticky note in a PDF and I think he was on a transatlantic flight when he reviewed this paper; the sticky note looks like it is pointing exactly to "The second metric is the lack of violations." He marked "We need to know the domains, the expected rate of violations in each domain, and then the actual degree of violations in each domain." with the same comment.