# Bootstraping and Resampling Statistics - Capability for non-normal variable data

R

#### Ravi Khare

Any experts around who can help?

Thanks.

R

#### Rick Goodson

It appears none of us have any experience in that area. I'll look around and if I can find any leads I will email you.

Rick

A

#### Atul Khandekar

Non-parametric

The entire theory & practice of SPC is heavily based on assumptions of 'normality'. However, in reality many of the processes are 'not normal'. Common practice is to use transforms to convert the data into an 'equivalent Normal' distribution.

I am looking for some information on what non-parametric methods are available, if any, for computing process capability regardless of distribution.

Can anyone provide any pointers to info on web / books?

Thanx,
-Atul

B

#### BRoyal

You might try Davis R. Bothe's book "Measuring Process Capability," McGraw-Hill publishes it. ISBN is 0-07-006652-3.

The book has a chapter on measuring capability for non-normal variable data.

Good luck.

Ben

R

#### Rick Goodson

Atul,

Take a look at the Weibull distribution as an alternative to the normal for estimating process capability witha non-normal distribution. The cumulative distribution function can be used to determine the portion of the distribution that exceeds a limit.

Dr. Donald Wheeler presented a paper at the 1991 ASQC Congress called "Shewart's Charts: Myth, Fact, and Competitors. It had some good information in it also. Unfortunately I can not find my proceedings or I would send you a copy. You might try his website Dr. Donald Wheeler for a lead on the proceedings.

Regards,

Rick

A

#### Atul Khandekar

Why distribution?

Thanx Ben and Rick. I'll look up the references you suggested.

Do we have to classify the data in distributions - normal and non-normal? Is it possible to work with just the numbers without trying to fit a distribution (non-parametric) and still calculate the process capability?
-Atul.

A

#### Atul Khandekar

This is one of the responses I have recieved from an other source:

"...Even with highly nonnormal data you're usually OK if you're using X-Bar R or X-Bar S charts, because the Rule of Averages takes care of the nonnormality (i.e since you're plotting averages instead of raw data, and averages are normally distributed, uou're OK). With variables charts, there's really only a problem when using Individuals charts - a nice solution to nonnormality there is to use EWMA charts instead of individuals charts. Again, since EWMA charts use averaging the points that are plotted become approximately normally distributed..."

Thanx.
-Atul.

T Use of OC Curves for Resampling Confidence - Sterilization based upon Z-1.4 Inspection, Prints (Drawings), Testing, Sampling and Related Topics 1
IEC 60601-1-8 clause 6.4.1 (statistics of the distribution of the sum of the maximum ALARM CONDITION + SIGNAL GENERATION DELAY) IEC 60601 - Medical Electrical Equipment Safety Standards Series 2
Statistics/sampling plan for medical device Inspection, Prints (Drawings), Testing, Sampling and Related Topics 10
Design Verification Testing and Statistics Reliability Analysis - Predictions, Testing and Standards 3
CQT Exam - Statistics Professional Certifications and Degrees 4
Simple statistics questions on labor data Statistical Analysis Tools, Techniques and SPC 2
Statistics and / or Forecasts on medical products exports from China Other Medical Device and Orthopedic Related Topics 1
What could go wrong with information: Ransomware statistics and facts (2018 to present) IEC 27001 - Information Security Management Systems (ISMS) 0
Good resources for learning statistics (quality engineering related) Statistical Analysis Tools, Techniques and SPC 10
Statistics - Where to start in ISO 9001? ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 5
Visitor Statistics - How to see a poster's stats easily? Elsmar Xenforo Forum Software Instructions and Help 3
D How do you use statistics in your job Statistical Analysis Tools, Techniques and SPC 6
Excellent Resource on Statistics / Lean / Six Sigma Book, Video, Blog and Web Site Reviews and Recommendations 2
Accelerated Learning and Simulations / Scenarios - Statistics Statistical Analysis Tools, Techniques and SPC 0
P Where to find conformance statistics for ISO 15189 Other Medical Device Regulations World-Wide 1
Statistics - Designs - Differences between Orthogonality and Confounding Using Minitab Software 5
M Statistics Question - What percent falls above 105? Statistical Analysis Tools, Techniques and SPC 2
A Assessing a Preventive Maintenance Strategy - Reliability or Maintenance Statistics Reliability Analysis - Predictions, Testing and Standards 2
Statistics and Sampling - Accounting for Failed Tests Statistical Analysis Tools, Techniques and SPC 10
Metrics and Statistics for Improvement - Easy to implement Statistical Analysis Tools, Techniques and SPC 4
C Statistics equation to determine the number of samples in a lot Statistical Analysis Tools, Techniques and SPC 8
ASQ CQE statistics training in Australia? Training - Internal, External, Online and Distance Learning 2
E Online Degrees and Graduate Certificates in Statistics Training - Internal, External, Online and Distance Learning 1
Guide to Microsoft Excel for Calculations, Statistics, and Plotting Data Excel .xls Spreadsheet Templates and Tools 11
C Basic Statistics Template .xls Document Control Systems, Procedures, Forms and Templates 0
S Statistics in Check/Replicate Analysis - HPLC Assay (Sample Duplicates) Statistical Analysis Tools, Techniques and SPC 1
R Student Question - Help needed with statistics questions Statistical Analysis Tools, Techniques and SPC 6
M The Statistical Meaning of "Muddy Middle" - Statistics Terminology Statistical Analysis Tools, Techniques and SPC 6
B Descriptive Statistics where the Data Type is Text? Using Minitab Software 4
R Industry Statistics on the benefits of Quality Management Systems ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 8
xkcd on Statistics and Mainstream Media Funny Stuff - Jokes and Humour 2
A R using RExcel - Non GUI Statistics Program Statistical Analysis Tools, Techniques and SPC 1
Job recovery? or "statistics don't lie, people do" Career and Occupation Discussions 37
G Statistics Question from Production and Operations Management Course Statistical Analysis Tools, Techniques and SPC 3
O Information on the extent of Statistics in the Six Sigma Green Belt Exam Professional Certifications and Degrees 9
J Gage R&R Module for R (Statistics Program) Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 4
T Survey or Statistics on the use of OHSAS 18001 Worldwide Occupational Health & Safety Management Standards 66
T Survey or Statistics on the use of the AS 9100 Standard Worldwide AS9100, IAQG, NADCAP and Aerospace related Standards and Requirements 2
H Elsmar Cove Statistics Found Online Coffee Break and Water Cooler Discussions 2
Quotable Quotes - Statistics Funny Stuff - Jokes and Humour 10
S Statistics of Gage R&R & Boundary Specifications Statistical Analysis Tools, Techniques and SPC 15
K Sample Statistics on HR (Human Resources) Key Processes ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 3
FDA released guidance on use of Bayesian statistics in Clinical Studies 21 CFR Part 820 - US FDA Quality System Regulations (QSR) 0
O Weighting Problems (Statistics) - Weight distribution for a machine setup Capability, Accuracy and Stability - Processes, Machines, etc. 5
S "Human Error" statistics Quality Manager and Management Related Issues 3
S ASQ CSSBB Exam & Knowledge of Statistics Professional Certifications and Degrees 3
Are there PPM statistics kept by Industry Manufacturing and Related Processes 4
Battery-Life Statistics After Work and Weekend Discussion Topics 4
F Error in Minitab (no statistics can be calculated with these data) Using Minitab Software 10
O The Basis of %GRR (% Gage R&R) and other Statistics - Minitab Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 21