Bioassay Blog Landing Page - Quantics Biostatistics

What is Relative Potency?

Relative potency (RP) refers to the dose of a test sample required to produce the same response in an assay as a dose of a reference sample. Since we... 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... read more →

24th August 2016
Francis Bursa
Bioassay

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... read more →

25th October 2016
Francis Bursa
Bioassay

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

We have previously discussed the 4 parameter logistic (4PL) model. This is a symmetrical S-shaped curve with the equation \[y=D+\frac{A-D}{1+e^{B\left(\log(dose)-C\right)}}\] for a response y. Sometimes you may see slightly... read more →

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... read more →

14th June 2017
Francis Bursa
Bioassay

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... read more →

26th July 2017
Francis Bursa
Bioassay

Response transformation: homogeneity of variance

Response Transformation: When and How?

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... read more →

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... read more →

15th December 2017
Ann Yellowlees
Bioassay

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... read more →

20th February 2018
Francis Bursa
All Blogs, Bioassay

Survival analysis for 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... read more →

19th March 2018
Ann Yellowlees
All Blogs, Bioassay

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... read more →

31st August 2018
Francis Bursa
All Blogs, Bioassay

How to Set Suitability Criteria for Relative Potency Bioassays

We previously discussed the purpose of system suitability tests and sample suitability tests and gave some examples of each. However, we did not explain how to actually set the limits... read more →

The Bursa – Yellowlees Method for Interpolation 5

ELISA Analysis: The Bursa-Yellowlees Method

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

pseudo-replicates: 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... read more →

6th September 2019
Ian Yellowlees
All Blogs, Bioassay

Pseudo-replicates and 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 →

31st January 2020
Ian Yellowlees
All Blogs, Bioassay

Bioassay Simulation: Reduce Lab Work

Bioassay simulation can be used during assay development maintenance to supplement and complement the information gained from lab experiments. Bioassay simulation assumes that the available real data is a... read more →

22nd April 2020
Ann Yellowlees
All Blogs, Bioassay

Vaccine Development: Correlates of Protection Explained

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... read more →

Failing Goodness-of-Fit: How to Combat the F-test Headache

We have all experienced the frustration (and sometimes utter dejection!) of performing a bioassay to what you thought was near perfection only to come back, analyse the data, and find... read more →

3rd November 2020
Ishara Fernando
All Blogs, Bioassay

Outliers – To Remove, Or Not To Remove?

It has been sometime since I have set foot in a lab, but the thought of seeing outliers in my data still sends a shiver down my spine –... read more →

22nd February 2021
Ishara Fernando
All Blogs, Bioassay

Accuracy, Precision and Bias

Accuracy and Precision are properties of an experiment which are often conflated - not least because they are often synonymous in everyday conversation. In science, however, they have separate,... read more →

9th August 2021
Ian Yellowlees
All Blogs, Bioassay

Zero Dose Control – An extra data point for free!

At the recent BEBPA meeting, in response to the question: 'If you have a zero dose control on your plate do you include it in your... read more →

29th October 2021
Ian Yellowlees
All Blogs, Bioassay

Choosing the best Parallel Line Analysis (PLA) software for your lab

Choosing the right Parallel Line Analysis (PLA) software for your lab is not an easy task. Whilst there are several packages available, and most can perform an adequate standard... read more →

17th March 2022
Ian Yellowlees
All Blogs, Bioassay

Statistical Model Formulae: The BEBPA Sessions

Myself, and my colleague Brooke, attended the BEBPA US virtual meeting last week and reported back on the presentation and round table discussions on relative potency software, including some... read more →

Fitting Algorithms: The BEBPA Sessions

This is the second mini blog responding to the software discussions at the BEBPA US 2022 conference. Blog One: Formulae - can be found here. The key driver for... read more →

Software: The BEBPA Sessions

This is the third blog responding to the software discussions at the BEBPA US 2022 conference. Blog One: formulae can be found here and Blog Two: Algorithms used can... read more →

R We Nearly Squared Yet? Why R² is a Poor Metric for Goodness-of-Fit

One of the most important metrics when analysing bioassay data is goodness-of-fit — how well does a dataset fit a chosen model? In development, this question can... read more →

Coefficient of Variation (CV) – a suitability criterion?

One of the most important concepts in bioassay is that of replication. Test samples are regularly replicated 2 or 3 times. Multiple response measurements at each dose will, in... read more →

26th October 2022
Jason Segall
All Blogs, Bioassay

R² II: What should you use to measure Goodness-of-Fit?

In the first part of this series, we investigated the use of the coefficient of determination—R2—to measure goodness-of-fit. Specifically, we showed that it is an inadequate tool: a... read more →

Understanding Cut-Point Analysis for ADA Assays

What are the most important properties of a new drug? Ultimately, we want to ensure that any new therapy treats what it is designed... read more →

20th December 2022
Jason Segall
All Blogs, Bioassay

Understanding Absolute and Relative Potency Assay for Optimal Results

Relative. Thanks for reading…But wait a moment! Have you ever stopped to ask why relative potency (RP) assays are the most common potency assay? Perhaps there are cases where... read more →

What is the 4PL Formula?

Picture the scene. You’re busily developing your assay and its data fits your chosen 4PL model beautifully. You’re just about to move onto validation—everything’s going so well!—but, out... read more →

15th March 2023
Ann Yellowlees | Taiki Yoshikawa and Jason Segall
All Blogs, Bioassay

What is Parallelism in Bioassay?

In the most basic sense, relative potency bioassays consist of a comparison of the behaviour of a reference standard to that of a test sample. That process is not... read more →

Un-confusing the Confidence Interval

A crucial acknowledgement of the scientific method is that no measurement will ever be perfect: results will always have associated variability, no matter... read more →

What is Bioequivalence?

One of the greatest challenges in the development of new drugs and therapeutics is that it’s just plain expensive. The average spend on a drug which passes clinical trial... read more →

The Confidence Interval II: Standard Error & Central Limit Theorem

In part 1 of our series covering the confidence interval, we examined some of the basic statistical concepts associated with a bioassay. In particular, we saw that a... read more →

11th September 2023
Matthew Stephenson | Jason Segall and Holly Trochet
All Blogs, Bioassay, Uncategorised

USP 1033: Top 3 Highlights from New Draft Guidances

The United States Pharmacopeia (USP) guidance on biological assay validation, General Chapter <1033>, will soon be updated. In the leadup to the publication of the new guidance,... read more →

Should I Average My Pseudo-replicates?

A common discussion we at Quantics have with our clients surrounds the issue of pseudo-replicates. It’s an area of tension between scientist and statistician – pseudo-replicates reduce the cost... read more →

9th November 2023
Liam Cann | Matthew Stephenson | Connie Stewart and Jason Segall
All Blogs, Bioassay

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