SV and CV are two essential parameter in earned value management and helps to analyze the project. If both are positive means project is progressing well but if one of the variance is negative then some corrective action are needed to bring the project back on track. I would prefer the project with CV positive and SV negative because this means that the project is under budget . Exceeding the planned budget is bad for you and also for stakeholders. Organization are sensitive towards any deviation from cost baseline that can effect the project specially when contract is price fixed and they have to put more money to complete the project. Negative SV doesn’t always means that project is behind the schedule in terms of target data at that moment. There are some delays and schedule have high probability of delay in future .Some activities are consuming the float of schedule and more activities tends to be critical. Sometime the project team is less efficient in utilizing the time allocated to project. To fix the problem effective risk management should be used . Sometime negative SV can be controlled by using critical path method.