Articles by Steven Walfish - BioPharm International

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Articles by Steven Walfish

Statistical Essentials—Part 4: Regression and Design of Experiments

A well-designed experiment can make it easier to understand the sources of variation.
Nov 1, 2008

Well-designed experiments can reduce the risk of coming to an incorrect conclusion during a process characterization, assay validation, or process validation study.

Minimizing the Problem of OOS

Out-of-specification situations can be reduced using confidence and tolerance intervals.
Sep 1, 2008

Statistical methods for calculating confidence intervals, tolerance intervals, and capability analysis to reduce out-of-specification situations.

The Power of Hypothesis

Although a powerful statistical method, hypothesis testing can lead to false conclusions if applied incorrectly.
Jun 1, 2008

How to use hypothesis correctly, and understanding the difference between one-sample, two-sample, and z-test.

Presenting Data Effectively

The key to a good graphical presentation is to select the method that best fits the data.
Feb 1, 2008

The key to a good graphical presentation is to select the method that best fits the data.

Analytical Methods: A Statistical Perspective on the ICH Q2A and Q2B Guidelines for Validation of Analytical Methods

Dec 1, 2006

Vagueness in the ICH Q2A and Q2B guidelines necessitates effective protocol design and data analysis. For specificity (detection in the presence of interfering substances), the goal is statistical differences with meaningful implications on assay performance. Linearity (results directly proportional to concentration of analyte in the sample) is typically demonstrated via least squares regression. Accuracy (difference between measured and true values) usually is presented as a percent of nominal. Precision analysis is vital because it supports claims of accuracy and linearity. A well-designed experiment and statistically relevant methods will facilitate method validation in accordance with ICH guidelines.

Final Word: Statisticians Tackle More Than Clinical Trials

Capitalize on their expertise for optimum productivity
Feb 1, 2006

Statisticians partner with technical experts to design statistically valid studies to construct the appropriate analysis.

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