Monitor and control operations demand deep interaction between users and devices, while they require the adoption of high interoperable solutions that only SOA-based Web Services can offer. When the access is performed via Internet using Web Services calls, the remote invocation time becomes crucial in order to understand if a service can be controlled properly, or the delays introduced by the wire and the serialization/deserialization process are unacceptable. We propose methodologies, based on a 2k factorial analysis and a Gaussian Majorization of previous service execution times, which enable the estimation of a generic remote method execution time.