Question

What is the relation between variation due to observation, manufacturing process and measuring process of a product?

(a) σobservation = σprocess + σmeasurement

(b) σobservation = σprocess – σmeasurement

(c) σobservation = σprocess * σmeasurement

(d) σobservation = σprocess / σmeasurement

I had been asked this question during an online interview.

The above asked question is from Calibration of Linear and Angular Measuring Instruments in division Testing and Calibration of Gauges and Dynamic Measurement of Engineering Metrology

Answer 1

Correct choice is (a) σobservation = σprocess + σmeasurement

The explanation is: The variation in the observation depends upon the variation in the product due to manufacturing process and variation due to measuring process. In order to keep  σobservation minimum measurement should be kept minimum so that product as a whole is reliable.