1. A method for combining process measurement data comprising: providing two or more process metrics from independent process sensors to form a set of process metrics; analyzing the process metrics within the set of process metrics to determine a consistency relationship between the process metrics; identifying outliers within the set of process metrics; generating a set of consistent process metrics from the set of process metrics; combining the process metrics within the set of consistent process metrics to generate a combined best estimate for the set of process metrics; generating an uncertainty value associated with the combined best estimate; outputting the combined best estimate for the set of process metrics with the uncertainty value if the process metrics are consistent with each other.