Quantifying risk in choosing the number of parts, operators and replicates in a GR&R

#1
Hello,

This is my first post so I hope this isn't breaking any rules. I did search for this to see if it was already posted and couldn't find it.

I am seeking advice on how to interpret the risk in determining the number of parts, operators and replicates in a GR&R.

For example, how can I communicate the risk in running different variations in the number of parts, operators and replicates. I'm used to running 10 part, 3 operators 3 times and am being asked why we can't reduce that because "it will take too long".

Is there some way to put it in terms of how confident we can be if we measure capability and how that is impacted by changing the number of parts, operators or replicates?

Thank you!
 
Elsmar Forum Sponsor

Bev D

Heretical Statistician
Staff member
Super Moderator
#2
Welcome Cleversn :bigwave:

you might find this page of a similar posting helpful...

I will say that the 10X3X3 approach is statistically and mathematically invalid. A better approach is detailed by Dr. Wheeler and my paper. The links can be found at the above page. If you read these two papers it will give you some things to really think about and come back with more questions...

A simple answer for you is that a measurement error study is intended to determine how much measurement error exists in relationship to the product variation and the specification range. measurement error and product variation are both quantified by their standard deviations. 10 parts is simply to small to create a useful estimate of either standard deviation. This is not a simple topic. It is complex and requires deep understanding and critical thought.

As for the "it takes too long" comment, well I guess that's true if you run a poorly designed study that can't really provide any insight especially if you just treat like a pass/fail 'check the box' thing to do. Speaking from years of experience I can't tell you how much more time, money and poor customer experience have resulted from not performing a simple well designed study that only takes a few hours to execute and analyze.
 
#3
Hi Bev!

Thank you for the response! I think I had come across your slides in my search before posting. I bet you have forgotten more about this subject than I will ever know. :)

I do have some follow up questions because there is a lot to unpack here. Luckily I'm able to conclude that since the 10x3x3 format is invalid reducing that to fewer parts/people/trials will be even less valid. So this partially address my original reason for posting.

1. My understanding of the "Honest GRR" is that it takes the percentages adding up to 100% into account (which makes sense) plus the math is different. I think I overlooked how this relates back to a 10x3x3 style. Does it change these variables or is it completely different?

2. I looked through all the links on this site (elsmar.com/elsmarqualityforum/attach-list/?filename=msa) and couldn't find a template for the "Honest GRR" format. I don't want to oversimplify it but I think that will help me visualize it. Do you know if one exists?

3. Am I correct in saying that completing the 10x3x3 is better than doing nothing? I'd definitely like to learn the "Honest GRR" but might need to put a pin in that so I can make some time to learn it enough to apply it.

Thank you!
 

Bev D

Heretical Statistician
Staff member
Super Moderator
#5
I do have some follow up questions because there is a lot to unpack here. Luckily I'm able to conclude that since the 10x3x3 format is invalid reducing that to fewer parts/people/trials will be even less valid. So this partially address my original reason for posting.

1. My understanding of the "Honest GRR" is that it takes the percentages adding up to 100% into account (which makes sense) plus the math is different. I think I overlooked how this relates back to a 10x3x3 style. Does it change these variables or is it completely different?
The Honest Gauge R&R paper points out the mathematical flaw in taking a ratio of two standard deviations - they will never add up to 100% and the way the math works in the popular method it grossly overstates the measurement error's contribution to the overall variation. This flaw is unrelated to the number of parts, repeated measures of each part or operators. The sample size numbers create a separate and distinct problem from the ratio of standard deviations.

2. I looked through all the links on this site (elsmar.com/elsmarqualityforum/attach-list/?filename=msa) and couldn't find a template for the "Honest GRR" format. I don't want to oversimplify it but I think that will help me visualize it. Do you know if one exists?
in addition to Miner's link - have just posted "MSA Tools" in the resources section, it will do the math and createe the plots for you. You must use only 2 repeated measures per part.

3. Am I correct in saying that completing the 10x3x3 is better than doing nothing? I'd definitely like to learn the "Honest GRR" but might need to put a pin in that so I can make some time to learn it enough to apply it.

[/QUOTE]
Don't confuse the sample size of 10X3X3 with the honest gauge R&R approach.
10X3X3 sample size can work with the honest gauge R&R math - although plotting it on a youden plot is impossible. The best way to learn is to just do it. get 30 parts measure them twice and enter the data into the spreadsheet. compare that with the results of measuring 10 of those 30 parts 3 times. it's really easy.
 
Thread starter Similar threads Forum Replies Date
M Quantifying "Risk" as a Usable Management Metric Quality Manager and Management Related Issues 3
D Quantifying Cost Benefits associated with a Particular Task Lean in Manufacturing and Service Industries 3
N Quantifying our QMS Objectives - Your Thoughts ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 12
I Quantifying the Effect of Excessive Within-Part Variation Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 1
D Quantifying the benefits of 5S Implementation Lean in Manufacturing and Service Industries 22
J Calculating Repeat Business for the purpose of quantifying a Quality Objective ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 2
Sravan Manchikanti Software Risk Management & probability of occurrence as per IEC 62304 IEC 62304 - Medical Device Software Life Cycle Processes 8
E Normal Condition Hazards in Risk Analysis ISO 14971 - Medical Device Risk Management 3
silentmonkey Rationalising the level of effort and depth of software validation based on risk ISO 13485:2016 - Medical Device Quality Management Systems 10
R Risk assessment on IT containers and the information they contain IEC 27001 - Information Security Management Systems (ISMS) 4
B Threat/Vulnerability Catalogue for risk assessment IEC 27001 - Information Security Management Systems (ISMS) 4
R Opportunity For Improvement vs Opportunity (Positive Risk) ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 18
R FOD Risk Assessment - What tools would you recommend for assessing FOD risk? AS9100, IAQG, NADCAP and Aerospace related Standards and Requirements 1
R Identify Medical Device characterstics as Annex C of ISO 14971 Risk Management ISO 14971 - Medical Device Risk Management 5
A ISO 14971 PFMEA Manufacturing Risk ISO 14971 - Medical Device Risk Management 2
Q Example of the Risk Template Document Control Systems, Procedures, Forms and Templates 1
K Overall residual risk according to ISO 14971:2019 ISO 14971 - Medical Device Risk Management 5
A Risk Number for each software requirement IEC 62304 - Medical Device Software Life Cycle Processes 7
A IEC 60601 11.2.2.1 Risk of Fire in an Oxygen Rich Environment, Source of Ignition IEC 60601 - Medical Electrical Equipment Safety Standards Series 0
D Importing a general wellness low risk product Other US Medical Device Regulations 3
R AQL, Consumer Risk and MA Statistical Analysis Tools, Techniques and SPC 2
M Risk managment report of Surgical Mask Example ISO 14971 - Medical Device Risk Management 14
M Risk Analysis Flow - Confusion between ISO 14971 and IEC 62304 IEC 62304 - Medical Device Software Life Cycle Processes 8
R ECG Risk Analysis Standards ISO 14971 - Medical Device Risk Management 2
N Device Labeling - Medtronic Ventilator Files (Risk Management documents) Coffee Break and Water Cooler Discussions 2
A 5 x 5 Risk Matrix - Looking for a good example Manufacturing and Related Processes 2
F Risk for Quality Assurance Department in a Hospital - Hospital Incident Reporting ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 7
M Should volume of sales be factored into risk probability assessments? ISO 14971 - Medical Device Risk Management 33
T How do you define your Hazards? <a Risk Management discussion> ISO 14971 - Medical Device Risk Management 16
adir88 Documenting Risk Control Option Analysis ISO 14971 - Medical Device Risk Management 8
B Risk Assessment Checklist for Non product Software IEC 62304 - Medical Device Software Life Cycle Processes 1
MrTetris Should potential bugs be considered in software risk analysis? ISO 14971 - Medical Device Risk Management 5
K Identification of hazards and Risk file IEC 62366 - Medical Device Usability Engineering 7
S Risk based internal auditing Internal Auditing 6
Robert Stanley I'm @ RISK of not showing my RISKS! ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 20
M Estimating the benefit-risk ration under MDR EU Medical Device Regulations 1
adir88 Information of safety can reduce risk now? ISO 14971 - Medical Device Risk Management 12
G Any good examples of CAPA forms that include a risk based approach? ISO 13485:2016 - Medical Device Quality Management Systems 8
adir88 MDR requirement: Risk Management Plan for "each device" ISO 14971 - Medical Device Risk Management 5
M Has anyone heard of Run at Risk? Manufacturing and Related Processes 15
Tagin Is SARS-CoV-2/COVID-19 on your risk register? Misc. Quality Assurance and Business Systems Related Topics 11
D IEC 62304 Risk Classification - With and without hardware control IEC 62304 - Medical Device Software Life Cycle Processes 2
J ISO 14971 applied to ISO 13485? Low risk class 1 devices ISO 13485:2016 - Medical Device Quality Management Systems 3
DuncanGibbons Classification of aerospace parts depending on their risk and criticality etc. Federal Aviation Administration (FAA) Standards and Requirements 3
D Performance specification as a Risk Control Measure, EN 14971 ISO 14971 - Medical Device Risk Management 7
M Risk Classification For Supplier - Clinical Research Organisation (CRO) Supply Chain Security Management Systems 3
Sidney Vianna IAQG SCMH explains "positive risk"..........but does it? AS9100, IAQG, NADCAP and Aerospace related Standards and Requirements 3
MrTetris Unacceptable risk and information for safety ISO 14971 - Medical Device Risk Management 16
M IATF 16949 (6.1.1 - Planning and Risk Analysis for a remote site) Process Maps, Process Mapping and Turtle Diagrams 5
D Risk Analysis & Technical File - What detail goes in the Risk Management Report ISO 14971 - Medical Device Risk Management 5

Similar threads

Top Bottom