EV, SV, and CV are mainly used as estimates so that the PM and stake holders can know where the project is at, and how it is doing. These values allow the PM to adjust, and make changes so that the project can be successful. As Jdc stated previously, Earned Value is dependent upon the percentage of work completed multiplied by the original budget of the project. Therefore to answer your question the values you calculate are simply a guideline to know where you at in the completion of your project. You cannot actually compare these values to what you will net gain upon completion of the project, but by looking at the SV, EV and CV you will be able to know if you need work harder and how much you can spend.