C4A – Valid Statistical Rationales for Sample Sizes

February 7, 2017 @ 10:00 am – 11:30 am



John N Zorich

This webinar explains the logic behind sample-size choice for several statistical methods that are commonly used in verification or validation efforts, and how to express a valid statistical justification for a chosen sample size.

The statistical methods discussed during the webinar include the following:

Confidence intervals
Process Control Charts
Process Capability Indices
Confidence / Reliability Calculations
MTBF Studies (“Mean Time Between Failures” of electronic equipment)
QC Sampling Plans

Why should you Attend: Almost all manufacturing and development companies perform at least some verification testings or validation studies of design-outputs and/or manufacturing processes, but it is sometimes difficult to explain the rationale for the sample sizes used in such efforts. This webinar provides guidance on how to justify such sample sizes, and thereby indirectly provides guidance on how to choose sample sizes. Those justifications can then be documented in Protocols or regulatory submissions, or can be given to regulatory auditors who may ask for them during onsite audits at your company. Thus, this webinar is designed to help you avoid regulatory delays in product approvals and to prevent an auditor from issuing you a nonconformity.

NOTE: This webinar does not address rationales for sample sizes used in clinical trials.

Areas Covered in the Session:
Examples of regulatory requirements related to sample size rationale
Sample versus Population
Statistic versus Parameter
Rationales for sample size choices when using…
Confidence Intervals
Attribute data
Variables data
Statistical Process Control C harts (e.g., XbarR)
Process Capability Indices (e.g., Cpk )
Confidence/Reliability Calculation
Attribute data
Variables data (e.g., K-tables)
Significance Tests ( using t-Tests as an example )
When the “significance” is the desired outcome
When “non-significance” is the desired outcome (i.e., “Power” analysis)
AQL sampling plans
Examples of statistically valid “Sample-Size Rationale” statements

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