Question

Consider the process of making and baking bread. Each of the following will cause variation in the process. Which of the following is/are special cause (assignable cause) variation? 1. The oven door is open for 90 seconds to check the bread while it is baking, II. The oven's thermostat allows the temperature to drift up and down slightly. III. The phone is answered and the bread is in the mixer too long. A. I and Ill only OB. I, II and III OC. Il and Ill only D. I and Il only OE. Il only

Answer 1

Answer

Assignable cause of variation in a process is unnatural and should be identified to make the process in stable condition and so that variation would be only due to the chance cause.

In the process of making and baking bread, the given cause of variation I - opening the door for 90 second to check the bread while baking can be controlled and III - answering the phone causing bread baked for too long also can be controlled. So these two are the only assignable cause which induces variation in the process because the both variation can be identified and controlled in process. The II cause of variation is due to chance that is natural cause of variation and the inherent part of the process variability.

So option (A) is correct.