INTRODUCTION TO MSA

 

Measurement System Analysis

TOPIC 5

Chapter 1

Measurement error  :

Measurement error is difference between value measured and true value. 

Measurement error is everywhere.

• Start with the assumption that every piece of data you see is wrong...

•  Your job is to figure out if the difference between actual and observed value matters.

Are you sceptical ?

Consider continuous data where every value has an infinite number of decimals.......

If you chop them off the result is not not totally accurate.

For example.

A file transfer took

14.157389210356943 seconds.

If you say,  " It took 14 seconds " , you would be wrong in the purest sense.

You decide :

Does the difference matter?

Why Measurement System Analysis

* Measurement System Analysis helps you understand difference between Actual Product / Process Quality and Quality of Measurement system and Observed Product / Process Quality.

* Shops use measurements to produce data to prepare control chart - X bar chart , R chart , X-MR chart, p- or c- charts etc . , to control processes.

* Creation of chart is as good as measured data - the tools and people engaged in the SPC process.

* Similar situation exist in acceptance sampling or DOE methods applied to assure quality.

* Measurement studies clarify all the doubt related to validity of the measurement system used to create SPC chart or to conduct Six sigma , DOE or any other quality assurance procedure.