Gigi thinks that children raised in a household without sibl…
Gigi thinks that children raised in a household without siblings earn higher incomes when they become adults, compared to people raised with one or more siblings. To test her idea, she consults census data and income data within her state, and compares the average salary earned by 1,000 people representing each group. Gigi is relying on __________ methods to address her question of interest.