A method includes defining a model of a process for manufacturing a device, the process including a plurality of steps. A plurality of inline process targets are defined for at least a subset of the process steps. The model relates the inline process targets to a plurality of process output parameters. A first set of probabilistic constraints for the inline process targets is defined. A second set of probabilistic constraints for the process output parameters is defined. An objective function is defined based on the model and the plurality of process output parameters. A trajectory of the process output parameters is determined by optimizing the objective function subject to the first and second sets of probabilistic constraints for each process step to determine values for the inline process targets at each process step, the optimization being iterated after completion of each process step for the remaining process steps.