# Determining Sample Size - AQL & LQ

S

#### SLEEPYMUM

Hi Folks,

My brain is currently mush from debating sample sizes, AQL/LQ & Pa.

Can some one please help in determining what sample size we should be using for the attribute inspection.

Customer gave the following spec:
1.5% AQL with and 8.2% LQ at Pa = 0.10

I do understand AQL/LP & Pa but trying to tie it together is confusing.

Our batch sizes will typically be 105,000

#### Mike S.

##### Happy to be Alive
Trusted Information Resource
Re: Sample Size AQL & LQ

A quick look at ANSI Z1.4 shows you could use single normal sampling, Gen Insp Level II, 1.5% AQL, sample size 500, Ac = 14, Re = 15, LQ = 4.0.

You could use an accept on zero plan with smaller sample, too.

EDIT: Looks like the plan that matches closest is level S4 (letter J) 80 pc sample size, LQ = 8.2, Ac = 3, Re = 4

S

#### SLEEPYMUM

Re: Sample Size AQL & LQ

Thanks for that, but whats confusing me is the customer is requesting 8.2% LQ...

Does this change the sample plan and accept rate?

#### Mike S.

##### Happy to be Alive
Trusted Information Resource
Re: Sample Size AQL & LQ

Thanks for that, but whats confusing me is the customer is requesting 8.2% LQ...

Does this change the sample plan and accept rate?
No, it is part of the characteristics of the plan. Whoever wrote the requirement should have just given you the sampling plan -- looks like they were testing you. Is this an academic pursuit or a real-world one?

S

#### SLEEPYMUM

Re: Sample Size AQL & LQ

No, this is for a new customer who is coming on board.
We currently use C=0 acceptance plans for our other customers, so the fact that AQL & LQ are listed in this new customer spec is what is confusing.

#### Mike S.

##### Happy to be Alive
Trusted Information Resource
Re: Sample Size AQL & LQ

If the customer did not object, you could use a 1.5% AAQL AOZ plan with a 56 piece sample size and LQ of 4.1 but it may be harder to meet than the Z1.4 plan that seems like it is the one the customer had in mind based on the LQ they quoted.

S

#### SLEEPYMUM

Re: Sample Size AQL & LQ

Hi,

If I put the data into Minitab, I am getting a sample size of 80, reject on 4....

This then calculates the OC curve....

DO these reference the ANSI tables?

#### Mike S.

##### Happy to be Alive
Trusted Information Resource
Re: Sample Size AQL & LQ

Hi,

If I put the data into Minitab, I am getting a sample size of 80, reject on 4....

This then calculates the OC curve....

DO these reference the ANSI tables?
Not sure I understand your question. But the Minitab output basically duplicated the Z1.4 plan I mentioned above from what it sounds like.

#### David-D

##### Involved In Discussions
Re: Sample Size AQL & LQ

Basically they're providing you the two critical points to curve-fit your sampling plan's OC curve to. There should be a broad range of sampling plans capable of doing that. You could also consider variable sampling plans if applicable (as with Z1.9). It doesn't seem to me that they're prescribing a specific plan from Z1.4 (or MIL-STD-105) but are instead describing the levels of customer and supplier risk they're looking to undertake. You could probably find a canned Z1.4/Z1.9 plan thats a pretty good match for your/their needs, or you could create one of your own.

David

Determining sample size for device sterility Inspection, Prints (Drawings), Testing, Sampling and Related Topics 3
Determining of sample size for 'Operational Qualification' AQL - Acceptable Quality Level 5
Determining Sample Size for Medical Device Component Validation Inspection, Prints (Drawings), Testing, Sampling and Related Topics 0
Surveillance Sampling Test - Determining Sample Size Inspection, Prints (Drawings), Testing, Sampling and Related Topics 5
S Determining sample size for inspection to achieve x% confidence re defects Misc. Quality Assurance and Business Systems Related Topics 10
Bayes Success-Run on Attribute Data - Determining Sample Size Statistical Analysis Tools, Techniques and SPC 2
Determining Sample Size in Design V&V activities 21 CFR Part 820 - US FDA Quality System Regulations (QSR) 44
G Determining Sample Size for Equipment Qualification Studies Qualification and Validation (including 21 CFR Part 11) 10
Determining Sample Size for Capability in Six Sigma Project Six Sigma 5
H Determining the Correct Sample Size when AQL points to two Sample Sizes AQL - Acceptable Quality Level 7
L Determining Cpk based on a given Sample Size, Confidence Level, & Reliability Inspection, Prints (Drawings), Testing, Sampling and Related Topics 2
M Determining Sample Size needed for Operational Qualification (OQ) Inspection, Prints (Drawings), Testing, Sampling and Related Topics 24
Determining the appropriate Sample Size using an AQL Table Inspection, Prints (Drawings), Testing, Sampling and Related Topics 29
J Functional Test Sampling - Determining Sample Size to eliminate 100% Testing Inspection, Prints (Drawings), Testing, Sampling and Related Topics 2
W Sampling Plan problem - Determining Sample Size for both Attribute and Variables Data ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 2
S Determining the Total Sample Size using AQL - AQL Lot Quantity question AQL - Acceptable Quality Level 8
1 Determining AQL and Sample Plan - Batch size is from 1-500 AQL - Acceptable Quality Level 24
E Determining Sample Size for Design Verification and Design Validation Other Medical Device and Orthopedic Related Topics 20
N Auditing Proof of Delivery signed by the customer - Determining Sample Size General Auditing Discussions 6
P Determining Sample Size - Filling a bag with three different types of candy Inspection, Prints (Drawings), Testing, Sampling and Related Topics 31
Q Determining Sample Size for FDA Verification and Validation Activities Inspection, Prints (Drawings), Testing, Sampling and Related Topics 41
D Determining sample size required based on a 95% confidence level Reliability Analysis - Predictions, Testing and Standards 7
B Determining sample size for drop test and waterproof testing Inspection, Prints (Drawings), Testing, Sampling and Related Topics 6
T Determining Receiving Inspection Sample Size Inspection, Prints (Drawings), Testing, Sampling and Related Topics 1
N Determining Sample Size for Attribute Data Inspection, Prints (Drawings), Testing, Sampling and Related Topics 3
C Internal Audit Sampling Plans - Determining Internal Audit Sample Size Internal Auditing 45
Q Determining the Appropriate Sample Size for Process Validation/Qualification Inspection, Prints (Drawings), Testing, Sampling and Related Topics 13
T Using Cpk for the purpose of determining sample size/frequencies Capability, Accuracy and Stability - Processes, Machines, etc. 2
G Determining Sample Size and Frequency for Features on Control Plans FMEA and Control Plans 8
R Determining Sample Sizes for Testing (Chemistry or Microbiology) Inspection, Prints (Drawings), Testing, Sampling and Related Topics 6
Selecting a Sample and Determining the Reference Value for a Bias Study Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 2
Determining the the maximum number of reprocessing cycles of attachments CE Marking (Conformité Européene) / CB Scheme 2
Determining Uncertainty from Gage R&R Gage R&R (GR&R) and MSA (Measurement Systems Analysis) 1
IATF 16949 4.3.1 - Determining the scope of the quality management system - supplemental IATF 16949 - Automotive Quality Systems Standard 9
ISO 9001:2015 4.3 Determining the Scope of the QMS ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 3
Determining SPC tolerance Statistical Analysis Tools, Techniques and SPC 21
Determining SAT Offsets vs TUS Offsets per SAE AMS 2750E AS9100, IAQG, NADCAP and Aerospace related Standards and Requirements 0
Question on determining defective units - I am not recording fixture to part rejected Statistical Analysis Tools, Techniques and SPC 5
Clause 8.2.2 Determining the requirements for products and services ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 5
Determining Calibration Frequency schedule for items used in production Manufacturing and Related Processes 2
Determining if Maintenance Contractor is an External Service subject to ISO 9001 Clause 8.4 ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 43
AS9100D PEAR - Examples for organization's method for determining process results? AS9100, IAQG, NADCAP and Aerospace related Standards and Requirements 5
Determining Calibration Tolerance of a Measurement Device General Measurement Device and Calibration Topics 2
ISO 17025 Documented Procedure for 6.2.5 - Determining competency ISO 17025 related Discussions 4
Determining FDA 820 (registration) vs ISO 13485 - Supplier gives us the kit ISO 13485:2016 - Medical Device Quality Management Systems 1
ISO 9001 8.4.1 - Determining controls applied to externally provided processes ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 8
Determining what is good and what is bad can be subjective - when is it a quality issue? ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 9
Determining what type of scrap to include in my internal PPM calculation Quality Manager and Management Related Issues 5
Determining number of employees within the "Scope" of the QMS ISO 9000, ISO 9001, and ISO 9004 Quality Management Systems Standards 9
Determining the Scope of the QMS during Stage 1? Registrars and Notified Bodies 11