A controller directs performance of a process having multiple process
parameters (MPPs), including a controllable process parameter (CTPP), a
targeted process parameter (TPP), a defined target value (DTV)
representing a limit on an actual average value (AAV) of the TPP over a
defined moving time period of length TPL.sub.AAV. A storage device stores
historical data representing the AVs of the TPP at various times over a
prior time period (PTP) having a length of at least TPL.sub.AAV. A
processor predicts future average values (FAVs) of the TPP over a future
time period (FTP) based on the stored historical data and the current
values of the MPPs. The processor also determines a target set point for
each CTPP based on the predicted FAVs, the current values of the MPPs and
the DTV, and directs control of each CTPP in accordance with the
determined target set point for that CTPP.