Question 1 (1 point) Which of the following may be considered as special causes which could affect process performance (select all that apply) Material from a new supplier untrained operator The natural variation of machine speed A process operating at its natural limits Question 2 (1 point) Which of the following are reasons for popularity of control charts. Select all that apply They are effective in defect prevention They prevent unnecessary process adjustments Nobody needs training as they are self-explanatory They are easy and cheap to implement Question 3 (1 point) Common cause variation is usually the result of using untrained or poorly trained operators True False