Discussions and insights

on statistical issues in life sciences

Bioassay Blog

Corrolates of Protection

Correlates of Protection Explained – Vaccine Development

Correlates of protection in determining vaccine efficacy is a topic of particular interest, given the current COVID-19 climate and the spotlight on vaccine development. Here at Quantics, we have a... read more →

4PL Simulation

Using Simulation in Bioassay to Reduce the Need for Laboratory Work

sim‧u‧la‧tion /ˌsɪmjəˈleɪʃən/ the activity of producing conditions which are similar to real ones, especially in order to test something, or the conditions that are produced.[i] In bioassay, simulation can be used during development stages and during assay maintenance, to supplement and complement... read more →

Replicates chart

Understanding True Replicates and Pseudo Replicates in Bioassay

This blog explains the difference between true replicates and pseudo replicates, and discusses the problems that may arise if this difference is ignored or misunderstood in bioassay statistical analysis. Quality... read more →

Pure Error Bioassay 8 doses

When is Pure Error for Bioassay an Error?

Software systems for calculating relative potencies and other bioanalytical results often provide a choice of variance estimation method, usually: Residuals, Lack of fit Error and Pure Error. This defines how... read more →

The Bursa – Yellowlees Method for Interpolation 5

The Bursa-Yellowlees Method for Interpolation Analysis

Interpolation analysis is used to find the concentration of a substance in a sample. For biologics, this is often used in ELISA analyses and other bioanalytic analyses. This blog... read more →

bioassay Simulation all

How to Set Suitability Criteria for Relative Potency Bioassays

In our last blog we discussed the purpose of system suitability tests and sample suitability tests and gave some examples of each. However, we did not explain how to... read more →

example suitability task

Understanding System and Sample Suitability Tests for Bioassay.

Suitability tests for bioassay are often confusing. In this blog, we discuss the two types of suitability tests: System suitability tests and Sample suitability tests. The blog is deliberately simplistic... read more →

Reduce animal use and improve the precision of your LD50 and vaccine challenge assays

LD50 assays and challenge assays both measure the time to an event, often death, for each animal. However the standard statistical approach to the analysis of the data treats the... read more →

Inhomogenous case C

How to Combine Relative Potencies for Bioassay

Welcome to our blog on combining relative potencies. In this blog, we’ll review the methods recommended by the United States Pharmacopeia (USP) and European Pharmacopoeia (PhEur) for combining relative potencies,... read more →

edgeeffect

Can we consign “The Edge Effect” to history?

We can waste about 40% of multi-well plates to avoid biasing the relative potency (RP) due to “the edge effect”. Quantics recently used a Latin square design to support a... read more →

DISTRIBUTION OF RESPONSE

When and How Should I Transform my Response Data?

Our clients sometimes tell us that they don’t want to use response transformations since it feels like an unwarranted manipulation of the data. However, there is little point in avoiding... read more →

Model AB Formula

Non-parallelism and Biosimilars

Many of our readers will be familiar with our paper “Parallelism in Practice” (PDA Journal of Pharmaceutical Science and Technology, 2015) and how we examined the common methods used for... read more →

Bioassay results

Inadvertent Consequences of Following a Guideline – European Pharmacopeia 9.2 section 5.3

Following the EurPh recommendations mixes up system and sample suitability and can lead to undesirable results. Assays failing when they should pass Assays passing when they should fail We recommend... read more →

5PL asymmetrical curve

Complications of fitting 4PL and 5PL models to bioassay data

Welcome to our fourth bioassay blog from Quantics Biostatistics. In our previous blog we discussed the 4 parameter logistic (4PL) model. This is a symmetrical S-shaped curve with the equation... read more →

tobit-loq

Reducing bioassay parallelism failures through better LOQ methodologies

As a slight change to our regular bioassay blog series where we last looked at the choice of statistical model when dealing with continuous response data. We thought we would... read more →

Choosing a statistical model: Continuous response data

In the last blog we discussed the definition of relative potency and how it relates to the concepts of biological similarity and thus the need for parallelism between the reference... read more →

What is Relative Potency?

Relative potency is a term used in bioassay to refer to the ability of a test sample, of unknown potency, to produce the desired response compared to a reference sample,... read more →

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