[tomp]

No, but it does introduce other variables.

E.g. age is important for lung cancer as well as smoking. Only when controlling for age do you get correct estimate about the danger of smoking.

What other variables does "Nigerian immigrants" introduce besides skin color and culture? The latter is eliminated by most US sociologists that keep screaming "it's not about culture!" so only race remains...

[InGoodFaith]

Isn't the fact that they immigrated likely bias towards the higher skilled echelon that managed to go through the visa process?

When you say "outperform most domestic US groups", are you normalising for the same skillset and education levels?

Perhaps a source to accompany your statement will help shed some light.

[karpierz]

Don't forget to control for:

- Wealth upon entry (If all Nigerian immigrants come from millionaire families, then it doesn't matter if they're underpaid; they'll be far wealthier than most Americans)

- Location (If all Nigerian immigrants live in New York City, then the effect size of being underpaid can be masked by the higher income (and cost of living) in New York City)

- Profession/Job Title (if all Nigerian immigrants are neurosurgeons, then it doesn't matter if they're underpaid; they'll be way above average income)

- Age (if all Nigerian immigrants are older, then they'll have had more time to generate skills/wealth, which could mask the effect of being underpaid)

- Health (if all Nigerian immigrants are healthy, then the effect of being underpaid could be masked by the fact that many Americans are less productive due to health issues)

There are obviously more confounders, but doing an analysis using these would be a good place to start to actually answer the question.