“…In industry, there are some situations when multiple assignable causes affected the model. Therefore, many researchers are interested in presenting a model in these situations (Gibra, 1981;Chung, 1991;Yang et al, 2010;Nenes et al, 2015;Ghanaatiyan et al, 2016;Tasias and Nenes, 2016;Salmasnia et al, 2017). Duncan (1971) extended his model from single assignable cause to multiple assignable causes where the assignable causes occurred independently.…”