Another less-than-cheerful finding of the NRRI is that the gradual rise in Social Security’s Full Retirement Age and low interest rates have acted as headwinds, making it tougher for American workers to manage retirement readiness.

In an effort to see whether the positive economic trends did more to help Americans in saving for retirement than the negative ones did to hinder them, researchers looked at NRRI results by age, income and pension coverage, then assesses the overall reasonableness of the NRRI’s findings, based on its conservative assumptions.

Some other studies “conclude that most Americans are saving optimally to meet their consumption needs in retirement, with less than 10 percent of households falling short.” But that’s based on two “key” assumptions: first, how children affect replacement rate targets, and second, how households consume their accumulated wealth in retirement.

These “optimal” assumptions regard households as having annuitized their financial assets and the proceeds of a reverse mortgage, “when few actually do so.” They also assume that households reduce their level of spending and increase their level of retirement savings on their own once their children are grown and gone—although this assumption too is often not the case.

Instead, households often remain at the same level of spending or only slightly reduce it, and few increase their savings level by as much as the optimal assumptions project. NRRI’s projections are closer to how American workers actually behave.

After reviewing all the data, the brief concludes that “half of today’s households will not have enough retirement income to maintain their pre-retirement standard of living, even if they work to age 65 and annuitize all their financial assets, including the receipts from a reverse mortgage on their homes. Instead, the study indicates that “many of today’s workers need to save more and/or work longer to achieve a secure retirement.”