²⁶One technical point to note about our estimation is that we impose the constraint that the Growth Impatience Condition (GIC), discussed in Carroll (2022), is never violated. (The GIC is required to prevent the ratio of total wealth to total income of any group from approaching infinity. It does this by making sure that the growth of wealth of the group is less than or equal to the growth of income.) The constraint is imposed by calculating an upper bound for the discount factors ${\beta }^{\text{GIC}}$ where the GIC holds with equality. The estimation procedure ensures that no type ends up with a discount factor higher than this upper bound.