We are exposed to this type of unit effect all the time. When we buy something for £9.99 we focus on the £9. When you are told a product costs just £1 a day rather than £30 a month and when a waiting time for treatment is 18 weeks rather than 4 and a half months.
The way we present information has a significant effect on the choices people make so we should consider that when giving health promotion advice.
How to Make a 29% Increase Look Bigger: The Unit Effect in Option Comparisons