Cost is the amount that we actually pay for a product or services. Worth is what we should pay for the functions which we want. So, the reasonable cost of the functions we seek is the worth of product. The objective of value engineering is to make cost close to worth:
If: Cost ~ Worth
Value = Worth (i.e. intended function)/Cost
~ 1
The objective of cost worth analysis is therefore to select areas of higher cost worth ratio because these areas are the potential areas of improvement through value and analysis.
Worth is applicable for the function and not for the product, services or system.