Trimmed Estimators for the Average and Standard Deviation

Abstract: The Distribution Analyzer software package identifies points that are potential outliers by reporting all values more than 4.5 standard deviations from the average. It uses robust estimators for the average and standard deviation to avoid potential outliers from biasing the estimates. Distribution Analyzer uses the trimmed estimators described in this article for this purpose. […]

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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.

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STAT-18: Statistical Techniques for Normality Testing and Transformations

This is part of a series of articles covering the procedures in the book Statistical Procedures for the Medical Device Industry. Purpose To provide guidance on normality testing to ensure the assumption of normality is adequately met when using variables sampling plans and related procedures. Related procedures include normal tolerance intervals, variables confidence limits for the

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STAT-16: Statistical Techniques for Equivalence Testing

This is part of a series of articles covering the procedures in the book Statistical Procedures for the Medical Device Industry. Purpose This procedure provides statistical techniques for demonstrating equivalence of a new product or process to an existing product or process. This is an alternate approach to demonstrating the product or process meets established requirements

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STAT-12: Verification/Validation Sampling Plans for Proportion Nonconforming

This is part of a series of articles covering the procedures in the book Statistical Procedures for the Medical Device Industry. Purpose This procedure provides tables and instructions for selecting sampling plans for FDA process validation and design verification to ensure they are based on a valid statistical rationale.  These determine the samples size and acceptance

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STAT-04: Statistical Techniques for Design Verification

This is part of a series of articles covering the procedures in the book Statistical Procedures for the Medical Device Industry. Purpose Design verification studies are confirmatory studies to ensure the product design performs as intended.  They make pass/fail decisions as to whether the product’s design outputs (specifications, drawings) ensure each design input requirement (requirements

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Normalized Individuals (IN) Control Chart

Abstract: The only commonly used control chart that cannot be normalized is the Individuals (I) chart.  A procedure called a Normalized Individuals (IN) chart is provided for normalizing data associated with an I chart.  The IN chart works nearly identical to the Laney U’ and P’ charts for count data.  The IN chart has certain theoretical advantages as

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Describing Compounder Accuracy

Suppose the accuracy of a compounder was described as ±5% or ±10%.  What does this mean to you?  In many ways, this description is lacking.  First, what percentage of dispenses would you expect to be in this range?  Is it 100%?  Is it 50%?  Does this statement describe the typical performance or a guaranteed level

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