The fuzzy upper and lower limits are calculated via
fuzzy operations as shown in Section 3. SDj, where
j=1,…, 30, is taken as a set and fuzzy estimators are
derived. k is taken as in the original Gulbay approach
after Monte Karlo simulation to be equal to 0.2795 in
order to minimize Type I errors (±3σ limits are replaced
by ±kσ limits). A chart of LCL, CL and UCL is
presented in Fig. 3.