After a two-day nationwide curfew, Iraq’s long-delayed and much anticipated census has now concluded and early results are in. The first for the country in nearly three decades, officials claim the data will reveal “the reality of Iraq in its smallest details,” and potentially revolutionize policymaking with data-driven insights.

Not all in Iraq are so sanguine on the poll’s expected results. Some in the Kurdistan region worry that new population numbers could serve to undermine Kurdish claims on Kirkuk and other “disputed territories.” Aiming to mitigate such concerns, political elites have chosen to exclude questions relating to ethnicity...