The article compares different ways of investing for retirement to see which is more likely to reach a specific target value. Instead of using complex math, the researchers used a simulation method to test various investment strategies. They found that sticking to a fixed mix of stocks and bonds (like 80% stocks and 20% bonds) is just as effective as gradually reducing stock investments over time. This means that changing your investments as you get older might not actually increase your chances of hitting your retirement goal.