# Manufacturing Sampling Plans

## Acceptance Sampling Standards

Updated October 1, 2018 Note:  Most of the standards below are specific to manufacturing applications.  A small number are also applicable to validation.  Those are specifically marked. Military Standards US military standards can be downloaded free of charge using the website quicksearch.dla.mil/qsSearch.aspx.  Searching by Terms works best.  Links are also provided for each military standard below. […]

## “Square Root of N plus one” Sampling Rule

Dr. Wayne A. Taylor The best that I can determine is that the rule probably had its origin in the USDA in the 1920-30’s.  But no confirming documents exist.   There are actually three versions of the rule: Take the square root of the lot size to get the sample size.  Accept on zero defects.   This

## Confidence Statements Associated With Sampling Plans

Suppose the single sampling plan with sample size n=50 and accept number a=1 is being used.  If a lot is accepted, one can state with 90% confidence that the lot is less than 7.56% defective.  Likewise, if the lot is rejected, one can state with 95% confidence that the lot is above 0.715% defective. The

## Selecting Statistically Valid Sampling Plans

INTRODUCTION Form 483 is used by the Food & Drug Administration (FDA) for reporting adverse findings resulting from one of their inspections.  Numerous 483’s have cited sampling plans as not being “statistically valid” or as lacking statistical justification.  So what does it take for a sampling plan to be statistically valid? Selecting statistically valid sampling

## Alternative Sample Sizes for Verification Dose Experiments and Dose Audits

Dr. Wayne A. TaylorJoyce M. Hansen ABSTRACT ISO 11137 (1995), “Sterilization of Health Care Products – Requirements for Validation and Routine Control – Radiation Sterilization”, provides sampling plans for performing initial verification dose experiments and quarterly dose audits.  Alternative sampling plans are presented which provide equivalent protection.  These sampling plans can significantly reduce the cost

## Acceptance Sampling Update

INTRODUCTION An understanding of statistical principles and how to apply them is critical to ensuring compliance with FDA requirements, such as those in the current and July working draft of the good manufacturing practices (GMP) regulation.   Indeed numerous Form 483’s issued by FDA following GMP inspections have cited sampling plans for final, in-process, and receiving

## Selecting Representative Samples

Dr. Wayne A. Taylor For the OC curve, AQL, and LTPD of a sampling plan to be valid, one must obtain representative samples of the lot.  Failure to select representative samples can seriously compromise the sampling plan’s protection.  Consider the analogy of dealing cards to obtain a fair hand.  If the deck is thoroughly shuffled,

## The Importance of Trending Attribute Data

Dr. Wayne A. Taylor The use of SPC is preferable to relying on acceptance sampling.  It is better to make defect-free product than to sort out the defects later.  However, with attribute data, care must be taken in implementing SPC to avoid only an illusion of change. Suppose a packing operation inspects for missing parts

## The Effect of Lot Size

Dr. Wayne A. Taylor Mil-Std-105E indexes sampling plans by AQL, Levels of Inspection, and lot size.  It is a common misconception that 105E includes lot size because “larger lots require more samples to obtain the same level of protection.”  In actuality, 105E takes more samples from larger lots in order to get better protection.  Figure 1

## Statistically Valid Sampling Plans

Dr. Wayne A. Taylor Numerous 483’s issued by the FDA have cited sampling plans as not being “statistically valid”.  So what is required of a sampling plan to be statistically valid?  Selecting statistically valid sampling plans is a two-part process.  First, one must determine an appropriate objective for the inspection.  Second, one must select a

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