The TERRIER program cost estimate is in constant FY 2011 dollars, while the SPANIEL program cost estimate is in constant FY 2014 dollars. Which one of the following is the most valid way of comparing the costs of these two programs?

1. Convert the TERRIER program cost to then-year dollars using the weighted index

2. Convert the TERRIER program cost to constant FY 2014 dollars using the raw index

3. Convert the SPANIEL program cost to constant FY 2011 dollars using the weighted index

4. Convert the SPANIEL program cost to then-year dollars using the raw index