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Statistical analysis of a micromethod in an interlaboratory test
Manfred Berres1, Rudolf Meier, Hans Reber
1University of Applied Sciences Koblenz, RheinAhrCampus, Südallee 2, D-53424 Remagen, Germany. berres@rheinahrcampus.de
Summary
This study validates a microbicidal testing method, demonstrating its reproducibility and repeatability across multiple laboratories. The findings confirm the method
Area of Science:
- Microbiology
- Analytical Chemistry
- Statistical Analysis
Background:
- A micromethod for microbicidal substance testing was developed by Meier in 1996.
- Interlaboratory testing is crucial for validating analytical methods' reliability.
- Assessing reproducibility and repeatability ensures consistent and accurate results.
Purpose of the Study:
- To evaluate the reproducibility and repeatability of the Meier (1996) micromethod.
- To determine the effective concentration of microbicidal substances using a nonlinear regression model.
- To provide guidance on interlaboratory test design and data analysis for microbicidal assays.
Main Methods:
- An interlaboratory test involving 7 laboratories with duplicate measurements over 5-9 days.
- Estimation of effective microbicidal concentration using nonlinear regression analysis.
- Data validation based on ISO 5725 standards, including model fit criteria, plausibility checks, and outlier detection.
Main Results:
- Approximately 85% of the data met inclusion criteria for analysis.
- Inter-laboratory and intra-laboratory reproducibility, along with repeatability, were computed.
- Confidence limits for relative precision were tabulated for various interlaboratory test designs.
Conclusions:
- The micromethod demonstrates sufficient reproducibility and repeatability for practical application.
- The study provides a framework for analyzing interlaboratory test data in microbicidal testing.
- Statistically sound test designs are presented for evaluating claimed effective concentrations of microbicidal substances.