Integrating ISO 22000, ISO 14001

Food safety testing, lab, standards

Q: In a food manufacturing company, with certifications to ISO 22000:2005 Food safety management systems — Requirements for any organization in the food chain as well as ISO 14001-2004: Environmental management systems – Requirements with guidance for use, the certification to ISO 22000 allows the company to operate with exemption from the Food Act. The exemption from Food Act determines that the organization has a permit to use its physical premises to indulge in industrial activity involving consumable food products.

Now, this permit is issued with certain conditions — e.g., regular updates to the issuing authority regarding changes to to the food safety plan. We view this requirement as a legal requirement.

My question is, would we use the legal register developed as part of ISO 14000 as the tool to manage the compliance to the above legal requirements? Doubt arises because the legal requirement addresses a condition imposed by the food safety system, but at the same time, if it is not complied with we could lose our license to operate (which I could interpret as an environmental aspect…license to exist).

Could someone kindly advise what they would consider to be a logical option?

Response from Susan Briggs:

A: I am not a food safety expert, so I  cannot give an opinion on whether or not using a register/process established for environmental regulations can be used for tracking food safety regulatory requirements.  But from the ISO 14001 perspective, and my professional opinion, the answer is “of course!.”

The intent of management system standards  — certainly all of the ones I have worked with– is to integrate the processes that are required by a standard (whether it be ISO 14001, ISO 22000, etc.) into the company’s business management process (i.e., a single process that is used to track all of the company’s legal obligations…environment, safety, finance, food safety, etc.), not to create stove piped processes (i.e., separate processes/systems for tracking depending on the nature of the regulation).

Susan Briggs
Director of Environment, Health and Safety, Textron Systems
Wilmington, MA
Chair, U.S. TAG to ISO/TC 207 on Environmental Management Systems

Response from John Surak:

A: I am not sure what is meant by the term “exemption from the Food Act.”  ISO 22000 requires that the organization meet all of the legal requirements of the country  in which the site is located.  In addition, if the organization is exporting food, they must meet all of the legal requirements of the target company.  ISO 22000 was developed to be compatible with the other ISO management system standards.  Therefore, it is fully permissible to develop an integrated management system as long as the management system meets the requirements of each standard and regulatory requirements.  I personally support the development of an integrated management system.  Sue conveyed this thought very well in her response.

Just one additional note, if the organization’s customers expect that the organization has a food safety management system that meets the requirements of Global Food Safety Initiative (GFSI), then the organization should seek registration to FSSC 22000 rather than ISO 22000.  FSSC 22000 is a food safety audit scheme that utilizes ISO 22000 and ISO 22002-1.

John G. Surak, PhD
Surak and Associates
Clemson, SC
A member of Stratecon International Consultants

For more on this topic, please visit ASQ’s website.

Applicability of TS 16949 to Non-Manufacturing Organizations

Automotive inspection, TS 16949, IATF 16949

Q: My conpany is certified to ISO 9001:2008 Quality management systems–Requirements. We provide integrated circuit chip design and outsource the manufacturing of the IC chips to our approved subcontractors. Recently, we won a contract to design and supply chips to one of our customers who, in turn, supplies to the automotive industry (the first automotive customer for my company).

One of the key deliverables of this project is to get ourselves certified to TS16949:2009 Quality management systems — Particular requirements for the application of ISO 9001:2008 for automotive production and relevant service part organizations in the next 6 to 9 months.

We would like to know:

1. Is TS 16949 applicable to a company, like mine, that does no manufacturing?

2. In general, what does it take to be at least compliant to the TS16949 requirements?

3. Since TS 16949 is based on ISO 9001 with additional requirements, does that mean that once a company is certified to TS16949 it is not necessary to recertify to ISO 9001?

A: Thank you for your questions.

The answer to your first question is that a company like yours is not eligible to become registered to TS 16949 because it is not a manufacturer.  Clause 1.1 General of TS 16949 states this very clear:

“This Technical Specification is applicable to sites of the organization where customer-specified parts, for production and/or service, are manufactured.”

Furthermore, clause 3.1.11 from Terms and Definitions defines a “site” as:

“Location at which value-added manufacturing processes occur.”

Your second question is about how to attain TS16949 compliance.  Simply, you would need to purchase a copy of TS16949 and ensure that your ISO 9001 quality management system meets all of the TS16949 requirements.  The biggest difference between ISO 9001 and TS16949 are the requirements associated with advanced product quality planning (APQP) and production part approval process (PPAP).

The answer to your third question is yes, registration to TS 16949 includes full compliance with all the requirements in ISO 9001.  A separate registration is not necessary.

If you have further questions, please don’t hesitate to ask.

Denis J. Devos, P.Eng
A Fellow of the American Society for Quality
Devos Associates Inc.
London Ontario

For more on this topic, please visit ASQ’s website.

ISO 2859-3 Skip-lot Sampling 5.1.1, 5.2.1

Suppliers, supplier management

Q: Our quality team is trying to improve inspection efficiency and enhance supplier management by employing ISO 2859-3:2005 Sampling procedures for inspection by attributes — Part 3: Skip-lot sampling procedures.

Here are two questions on product qualification related to clause 5.2.1 Generic requirements for product qualification.

1. The standard requires that:

b) The product shall not have any critical classes of nonconforming items or nonconformities.

First, my understanding is that the risk level with any potential failure or nonconforming of the product should be low to customer — is this correct? Second, if a candidate product carries some critical features (dimension of mechanical product), but also carries a number of low risk features, can we apply the skip lot concept only to the non-critical features? And continue to perform lot-by-lot inspection with critical features? We are concerned the definition of “product” in the standard is a generic term and could be interpreted as feature of a physical product.

2. The standard requires that:

c) The specified AQL(s) shall be at least 0,025 %.

Does this mean the AQL value should be less than or greater than 0.025%? I assume “greater.” In our company, the most often used is AQL 1.0 and AQL 2.5, which I think meets the requirement.

We would greatly appreciate your help.

A: My name is Dean Neubauer and I am the U.S. Lead Delegate to Subcommittee 5 on Acceptance Sampling and Quality Press author. I hope I can help you.

Let’s start with question 1.

The general idea of skip-lot sampling is to reduce the number of times incoming lots inspected due to exceptional quality on behalf of the supplier.  ISO 2859-3 states this in the beginning as:

The purpose of these procedures is to provide a way of reducing the inspection effort on products of high quality submitted by a supplier who has a satisfactory quality assurance system and effective quality controls.

The reduction in inspection effort is achieved by determining at random, with a specified probability, whether a lot presented for inspection will be accepted without inspection.

A skip-lot sampling plan is also known as a cumulative results plan.  In general, such plans require certain assumptions to be met regarding the nature of the inspection process:

  • The lot should be one of a continuing series of lots
  • We expect these lots to be of the same quality
  • The consumer should not expect that any lot is any worse than any of the immediately preceding lots
  • The consumer must have confidence in the supplier not to pass a substandard lot even though other lots are of acceptable quality

Under these conditions, we can use the record of previous inspections as a means of reducing the amount of inspection on any given lot.  ISO 2859-3 states the above in 5.1.1 Requirements for supplier qualification:

The requirements for supplier qualification are as follows.

a) The supplier shall have implemented and maintained a documented system for controlling product quality and design changes. It is assumed that the system includes inspection by the supplier of each lot produced and the recording of inspection results.

b) The supplier shall have instituted a system that is capable of detecting and correcting shifts in quality levels and monitoring process changes that may adversely affect quality. The supplier’s personnel responsible for the application of the system shall demonstrate a clear understanding of the applicable standards, systems and procedures to be followed.

c) The supplier shall not have experienced any change that might adversely affect quality.

The underlying assumption here is that the supplier quality is exceptional (low nonconforming level).  The skip-lot plan is applied to each characteristic, or feature, separately.  If several characteristics are present, then try to test for at least one of them.  In your situation, if you have critical characteristics you should not be doing skip-lot inspection due to the risk of ignoring (skipping) a potentially dangerous lot.  On the other hand, you can use a skip-lot plans for non-critical (major and minor) nonconformities and they will have different AQL levels associated with them.  Your listing of AQLs of 1.0% and 2.5% are typical for major and minor nonconformities.  Critical defects will typically have an AQL less than 1.0%, such as 0.25% to 0.65% (0% is preferred but theoretically unattainable as you would have to do a perfect 100% inspection, i.e., no inspection error).

The subclause referenced in question 2 states that the AQL level must be greater than or equal to 0.025%. Your levels of 1.0% and 2.5% can be used.

Dean Neubauer

U.S. Lead delegate for Subcommittee 5 on Acceptance Sampling on ISO Technical Committee 69 on Applications of Statistical Methods.

For more information on this topic, visit ASQ’s website.

Variation in Continuous and Discrete Measurements

Force majeure

Q: I would appreciate some advice on how I can fairly assess process variation for metrics derived from “discrete” variables over time.

For example, I am looking at “unit iron/unit air” rates for a foundry cupola melt furnace in which the “unit air” rate is derived from the “continuous” air blast, while the unit iron rate is derived from input weights made at “discrete” points in time every 3 to 5 minutes.

The coefficient of variation (CV), for the air rate is exceedingly small (good) due to its “continuous’ nature” but the CV for iron rate is quite large because of its “discrete nature,” even when I use moving averages for extended periods of time. Hence, that seemingly large variation for iron rate then carries over when computing the unit iron/unit air rate.

I think the discrete nature of some process variables results in unfairly high assessments of process variation, so I would appreciate some advice on any statistical methods that would more fairly assess process variation for metrics derived from discrete variables.

A: I’m not sure I fully understand the problem, But I do have a few assumptions and possibly a reasonable answer for you. As you know, when making a measurement, using a discrete scale (red, blue, green; on/off, or similar), the item being measured is placed into one of the “discrete” buckets. For continuous measurements, we use some theoretically infinite scale to place the units location on that scale. For this latter type of measurement, we are often limited by the accuracy of the equipment to the level of precision the measurement can be accomplished.

In the question, you mention measurements of air from the “continuous” air blast. The air may be moving without interruption (continuously), yet the measurement is probably recorded periodically unless you are using a continuous chart recorder. Even so, matching up the reading with the unit iron readings every 3 to 5 minutes, does create individual readings for the air value. The unit iron reading is a “weights” based reading (not sure what is meant by derived, yet let’s assume the measurement is a weight scale of some sort.) Weight, like mass or length, is an infinite scale measurement, limited by the ability of the specific measurement system to differentiate between sufficiently small units.

I think you see where I’m heading with this line of thought. The variability with the unit iron reading may simply reflect the ability of the measurement process. I do not think either air rate or unit iron (weight based) is a discrete measurement, per se. Improve the ability to measure the unit iron and that may reduce some measurement error and subsequent variation. Or, it may confirm that the unit iron is variable to an unacceptable amount.

Another assumption I could make is that the unit iron is measured for the batch that then has unit air rates regularly measured. The issue here may just be the time scales involved. Not being familiar with the particular process involved, I’ll assume some manner of metal forming, where a batch of metal is created then formed over time where the unit air is important. And, furthermore, assume the batch of metal takes an hour for the processing. That means we would have about a dozen or so readings of unit air for the one reading of unit iron.

If you recall, the standard deviation formula is divided by square root of n (number of samples). In this case, there is about a 10 to 1 difference in n (10 for unit air to one for unit iron). Over many batches of metal, the ratio of readings remains at or about 10 to 1, thus impacting the relative stability of the two coefficient of variations. Get more readings for unit iron or reduce the unit air readings, and it may just even out. Or, again, you may discover the unit iron readings and underlying process is just more variable.

From the information provided, I think this provides two areas to conduct further exploration. Good luck.

Fred Schenkelberg
Voting member of U.S. TAG to ISO/TC 56
Voting member of U.S. TAG to ISO/TC 69
Reliability Engineering and Management Consultant
FMS Reliability

For more on this topic, please visit ASQ’s website.

Restructuring an Internal Auditing Program

Reporting, best practices, non-compliance reporting

Q: For the last 15 years, my company has employed a small cadre of full-time, dedicated safety management system auditors.

A current proposal in our company is to recast those auditors as HES Superintendents under the supervision of an operations or safety manager who has significant management responsibility within the safety management system.  This change will give HES Superintendents (persons performing audits) additional, non-audit tasks for performance on the premises of the auditee immediately before, during or after the audits.  Those non-audit tasks could include workforce training, management mentoring and evaluation, facility inspection, etc. In addition, this change will reduce about 50% of the number of audits performed per person in a given time period.

My concerns are as follows:

•  Supervision of the HES Superintendents (especially assignment, evaluation and compensation determination) by an operations manager, safety manager, or someone under their supervision, could constitute auditee control of the audit program, and a thwarting of the principle of auditor independence.

•  The addition of non-audit tasks to auditors’ work seems to open possibilities for audit conflicts of interest. Since HES Superintendents will participate materially in the ongoing safety management of the company, their independence and impartiality as safety management system auditors would be subject to question.

•  The 50% reduction in number of audits per auditor would result in dilution of auditors’ audit experience and therefore their expertise, leading to attenuation of the company’s capability to audit expertly.

In terms of the principles of management system auditing, are my concerns valid?

Do you know of other instances of this part-time-auditor approach being used in high-risk industries?

Any comment on the wisdom of this proposal?

Occasionally, multiple experts offer their expertise and viewpoints to assist quality practitioners. Add your voice by commenting on posts!

Bill Aston’s take:

A: You’ve mentioned valid concerns that should be assessed by top management prior to restructuring their organization’s audit program.  As I understand your concerns, they include two primary items:

1.    To ensure that the restructure of the audit program continues to provide auditors with independence, objectivity and impartiality from the processes and process owners to be audited.

2.    Potential result of a 50% reduction of the number of audits conducted per auditor diluting auditor experience and expertise.

With regard to the first item, this is a matter that top management should thoroughly evaluate to ensure that the requirements of ISO 9001:2008 — Quality management systems — Requirements, clause 8.2.2b internal audit, continue to be met.  This clause requires that The selection of auditors and conduct of audits shall ensure objectivity and impartiality of the audit process.  Auditors shall not audit their own work.

In addition, although the requirements in ISO 19011:2011– Guidelines for auditing management systems are not auditable requirements, section 3.1, Terms and Definitions, (note 1), does mention the need for ensuring internal auditor independence.

The key point is that your organization’s registrar will most likely look very closely at how the audit program has been restructured to ensure that auditor independence, objectivity and impartiality have been maintained.

Regarding item number two, although maintaining an auditor’s level of expertise and experience are important, the primary purpose of internal audits is to assess the effectiveness and continual improvement of the quality management system and its processes.  If maintaining auditor expertise and experience becomes an issue due to the reduction in the number of available audit assignments, management should consider adjusting the number of auditors needed to meet the actual workload.

As you’re aware, ISO 9001:2008 requires internal audits to be conducted at planned intervals, but it does not prescribe any frequency for performing audits.  So this area is strictly a decision that must be made by each organization to meet their own specific requirements to ensure the continual improvement of the quality management system (QMS).

In summary, ISO 9001:2008, clause 5.4.2b Quality management system planning, requires top management to ensure that the integrity of the quality management system is maintained when changes are planned and implemented.  This includes the restructuring of processes such as the audit program.  Internal audits are one of the most important tools that an organization has to assess the effectiveness and continual improvement of their quality management system.   Therefore, it’s essential that the personnel performing these audits are trained, experienced and independent of the area being audited.

It has been my experience that there are few organizations that maintain a staff of fulltime QMS auditors.  Most organizations utilize staff personnel who are familiar with the processes to be audited and have been trained and are experienced as auditors.  Although they perform audits, this is usually not their only responsibility.  However, in some cases, large organizations may have one or two fulltime auditors who function corporate-wide and are supported by trained and experienced staff personnel on an as needed basis.

I hope this helps.

Bill Aston
ASQ Senior Member
Managing Director of Aston Technical Consulting Services
Kingwood, TX

Thea Dunmire’s take:

A: Given that this question involves audits of a safety management system rather than a quality management system, the more applicable standard would likely be OHSAS 18001:2007 Occupational health and safety management systems – not ISO 9001:2008.  However, OHSAS 18001 also specifically states – “Selection of auditors and conduct of audits shall ensure objectivity and the impartiality of the audit process.”  Although OHSAS 18001 does not include the statement – “Auditors should not audit their own work,” that is definitely true.   As a general rule, auditors should not audit activities for which they are responsible or accountable.

It is common for organizations to utilize individuals as internal auditors who have other staff responsibilities.  Few organizations have dedicated environmental, health and safety management system auditors.  Most internal environmental health and safety (EHS) auditors have other responsibilities.  In addition, based on surveys conducted by the Auditing Roundtable, the overall management of the EHS audit program is often located within the EHS department, not in a separate internal audit function.  This can make ensuring the independence of the EHS audit program very challenging.

The important question isn’t whether specific individuals are auditing full or part time. Instead, it is whether all of the auditors utilized within the audit program have the appropriate independence, competence and resources to conduct the audits they have been assigned.  Independence I have discussed above.  By competence, I mean the general knowledge and skills needed for management system auditing (as set out in clause 7.2.3 Possess appropriate knowledge and skills of ISO 19011) as well as technical expertise appropriate for their audit assignments.  By resources, I mean that there is sufficient support, including adequate time, to conduct the individual audits needed to meet the objectives established for the audit program.

Identifying the resources needed for the audit program is one of the key responsibilities of the person assigned the role of audit program manager (as set out in clauses 5.3.1 Perform audit program management tasks and 5.3.6 Identify program resource requirements  of ISO 19011:2011).  Lack of adequate resources is a common weakness of many internal audit programs.  Often, internal audit programs have very broad and expansively-stated objectives, but lack the resources needed to achieve these objectives.  It is the audit program manager’s responsibility to point out this disparity to top management.  The solution is for top management to either adjust the objectives of the audit program, taking into account the policy commitments made by the organization, or provide more resources for the internal audit program.

A key requirement of a safety management system is identifying the organization’s legal and other requirements to which it subscribes.   These identified requirements must be taken into account when establishing management system programs and procedures.  This includes any legal obligations associated with establishing and maintaining internal audit programs.  For example, for organizations subject to the BOEMRE regulations (offshore oil and gas), the Safety Environmental Management System  (SEMS) regulations require that auditors be qualified and independent (see 30 CFR 250.1926).  Legal requirements, as well as the commitments made by the organization in its occupational health and safety policy (or its sustainability reports), must also be taken into account when identifying the resources needed for the EHS audit program.

Internal audits are one of the important ways of assessing the effectiveness of a management system.  The audit program itself should be reviewed to determine its effectiveness in accomplishing this task.  Changes can, and should, be made to internal audit programs but the potential impacts of proposed changes need to be fully assessed in light of the organization’s policy commitments and its legal obligations.

Here is a link to the Auditing Roundtable survey results I mentioned: AR Member Survey Results – Organizational Location of the EHS Audit Program

Thea Dunmire, JD, CIH, CSP
ENLAR Compliance Services, Inc.
Largo, FL

Jim Werner’s take:

A: This is indeed a unique question.  I read and re-read this question over and over, and I have come up with the same opinion – “it depends.”  I am assuming “audit” is referring to an independent review of the quality system.  Some places use the term “audit” to mean an inspection activity.  If the past audits have consistently demonstrated the effectiveness of the quality system, then it is appropriate to reduce the number and frequency of the audits.

As far as the re-organization of the staffing of the auditing function – this is a management decision.

Jim Werner
Voting member to the U.S. TAG to ISO TC 176
Medical Device Quality Compliance (MDQC), LLC.
ASQ Senior Member

For more on this topic, please visit ASQ’s website.

Could Null Hypothesis State Difference?

About ASQ's Ask the Standards Expert program and blog

Q: Does a null hypothesis always state that there is no difference?  Could there be a null hypothesis that claims there is?

In the U.S. legal system, the null hypothesis is that the accused is assumed innocent until proven guilty.  In another legal system, there might exist the possibility that the accused is assumed guilty until proven innocent.  In our system, a type 1 error would be to find an innocent man guilty.  What would be considered a type 1 error if the null hypothesis was assumed guilt?

A: Sir Ronald Fisher developed this basic principle more than 90 years ago.  As you have correctly stated above, the process is assumed innocent until proven guilty. You must have evidence beyond reasonable doubt. An alpha error (type 1) is calling an innocent person guilty. Failure to prove guilt when a person really did commit a crime is a Beta error (type 2).

What can null hypothesis tell us?  Does the confidence interval include zero (or innocence in the court example)? Instead of asking, “can you assume guilt and prove innocence?” — turn the question around and ask “does the confidence interval include some value that is guilty?”

For example, let’s say a process has an unknown mean and standard deviation, but it has customer specifications from 8-12 millimeters. Your sample measures 14 millimeters. Clearly, your sample is guilty by customer specifications. We need to prove beyond reasonable doubt that the confidence interval of the process, at some risk level (alpha), does not include guilty material. This is done by measuring the process for control.  If it is in control and not meeting customer specifications, either move the distribution, reduce the variation (through Design of Experiments, or other methods), or through some combination of both.

If the new confidence interval does not include guilt, the argument would be that you have proven, beyond reasonable doubt, that the confidence interval does not include the out-of-spec material. Under this circumstance, a type 1 error (alpha error) would be a process  mean less than the upper specification, but the confidence interval included the specification.

Bill Hooper
ASQ Certified Six Sigma Master Black Belt
President, William Hooper Consulting Inc.
Naperville, IL

For more on this topic, please visit ASQ’s website.

Service Quality Manual Sample

ISO documentation practices, requirements


I have just started in a new position.  I was wondering if you have available a “sample” of a services quality management program manual?  And/or “sample” policies and procedures which a service organization would normally have?


Thank you for contacting ASQ.  ASQ offers sample quality manuals, in a variety of file formats.  Here’s a summary of what the sample manual contains:

“The example quality manual (QM) is designed for a service-providing organization that wishes to demonstrate conformance to the requirements of ANSI/ISO/ASQ Q9001-2008 American National Standard: Quality management systems — Requirements. The example manual also demonstrates that a single manual can be used to show conformance or compliance to a number of additional requirements, such as government regulations. There is no need to have a separate QM for each, but it is advisable to have a matrix showing how the QM addresses each set of requirements. In this case, the example QM is for an imaginary US airline, so certain items of the Federal Aviation Regulations are addressed. Examples of other different areas that could be addressed in a QM include health and safety, environmental concerns, financial accounting, corporate ethics, major customer requirements, and more. The idea is that the “quality manual” should not be a static document seen only by the “quality” department – it should be a dynamic business operating manual that describes “how we do business” everywhere in your organization.”

Accuracy of Measurement Equipment

Automotive inspection, TS 16949, IATF 16949

Q: I work for an incoming quality assurance department. In our recent audits, the auditor claimed that high precision machines such as the Coordinate Measuring Machines (CMM) and touchless measurement system should have higher Gage Repeatability and Reproducibility (GR&R) values compared to less precise equipment such as hand-held calipers and gages. If this is the case, does Measurement System Analysis (MSA) cater to this by providing a guidance on what are the recommended values for each measuring equipment by general? If not, should we still stick to the general MSA rules, regardless of the equipment’s precision value?

A: When you noted “higher GR&R values,” that in itself can be a bit confusing because the GR&R value is a percentage of errors caused by repeatability and reproducibility variation. The higher the number, the more variation present — and the worse the measurement method is.

As far as I know, MSA doesn’t give specific guidance for recommended values depending on the measuring equipment. Also, I’m not sure of the validity of saying that a CMM is consistently more accurate than other equipment, such as calipers. Although the equipment may theoretically be more accurate, how you stage the part to be measured will also affect the amount of variability, as will the feature being measured.  Consequently, even though the CMM is theoretically more accurate, there may be 20 percent GR&R, mainly due to the holding fixture or the feature being measured. I’m sure you get the point here.

As far as I know, MSA manuals do discuss what the major inputs should be when deciding the amount of acceptable variation. It strongly recommends to look at each application individually to verify what is required and how the measurement is going to be used.

Another thing to consider is whether you are looking at the GR&R based on total variation or on the specified tolerance. Tolerance-based is more commonly used than total variation, but that may depend on the type of industry.

One thing I would like to mention is that if you have three people take 10 measurements each, and then dump the information into one of the common software programs, it will not matter if they take the 10 measurements with a dial caliper or with a CMM. The instruments’ “accuracy” should not be the deciding factor, but the tolerance base should be.

Also, ISO standards do not dictate GR&R values. If you do what your quality management system says you do, most auditors will not push such an issue. While some auditors may offer “opinions” and suggestions, such items are rarely cause for nonconformance findings.

I hope this helps answer your question.

Bud Salsbury
ASQ Senior Member, CQT, CQI

For more on this topic, please visit ASQ’s website.

ANOVA for Tailgate Samples

Automotive inspection, TS 16949, IATF 16949

Q: I have a question that is related to comparison studies done on incoming inspections.

My organization has a process for which it receives a “tailgate” sample from a supplier and then compares that data with three samples of the next three shipments to “qualify” them. The reason behind this comparison is to determine if the production process of the vendor has changed significantly from the “tailgate” sample, or if they picked the best of the best for the “tailgate.”

It seems a student’s t-test for comparing two means might be a simple and quick evaluation, but I believe an ANOVA might in order for the various characteristics measured (there are multiple).

Can an expert provide some statistician advice to help me move forward in determining an effective solution?

A: Assuming the data is continuous,  ANOVA (or MANOVA for multiple responses) should be employed. Since the tailgate sample is a control, Dunnett’s multiple comparison test should be used if the p-value from ANOVA is less than 0.05.  If the data is discrete (pass/fail), then comparing the lots would require the use of a chi-square test.

Steven Walfish
Secretary, U.S. TAG to ISO/TC 69
Principal Statistician, BD

For more information on this topic, please visit ASQ’s website.