1Q automatically balances as closely as possible to the national census for audiences containing at least 30 members
We also have a National Polling feature, which allows our algorithms to determine the most nationally representative set of respondents (by matching gender, race and region) based on census data. To do this you need to select National Poll on the demographics page.
The national polling option can only be used with a minimum of 100 respondents and when no other demographic filters are set.