Optimal experiments for time-dependent mineral processes
by
Denny Meyer
Massey University, Albany Campus, Auckland
Coauthors: Tim Napier-Munn

Time dependence is an important characteristic of mineral processing plant data. This paper investigates the optimum form of experimental design for such data. Two intuitive approaches for the design of experiments involving time dependent data have been disproved recently. Firstly Cheng and Steinberg (1991) have shown that in some circumstances systematic experiments are preferable to replicated randomised block designs. Secondly, Saunders and Eccleston (1992) have shown that rather than sampling at a frequency which ensures independent data, in some circumstances sampling intervals should be as small as possible. A third issue raised in this paper concerns the use of standard statistical tests when the data are serially correlated. It is shown that the simple paired t-test, suitably modified for time dependence, is appropriate and easily adapted to allow for a covariate and a sequential analysis. The results are illustrated using recovery data for a Bougainville Copper Limited experiment (Napier-Munn, 1995).

Date received: April 4, 2002