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 →

4th July 2016
All Blogs, Bioassay

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
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
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 →

4th April 2017
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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
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
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 →

29th August 2017
Bioassay

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
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
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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
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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
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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 →

15th February 2019
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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 →

7th June 2019
All Blogs, Bioassay, Uncategorised

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
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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
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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
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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 →

3rd June 2020
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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
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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
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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
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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
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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
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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 →

14th April 2022
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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 →

17th May 2022
All Blogs, Bioassay, Bioassay DE

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 →

14th June 2022
All Blogs, Bioassay, Bioassay DE

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 →

6th October 2022
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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
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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 →

30th November 2022
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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
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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 →

8th February 2023
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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
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 →

5th April 2023
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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 →

8th August 2023
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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 →

22nd August 2023
All Blogs, Bioassay, Clinical

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
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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 →

20th September 2023
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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
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Statistical Software Validation: A Risk-Based Approach

Validation of statistical software is required for use in regulatory work. Many auditors expect to see the traditional IQ, OQ, PQ approach applied to the base system (SAS, R,... read more →

1st December 2023
All Blogs, Bioassay, Clinical

How to Build a Confidence Interval

In parts 1 & 2 of our series on the confidence interval, we have covered some of the basic statistical concepts – means, standard deviations, and distributions –... read more →

19th December 2023
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Bioassay Optimisation: Save time, Save Money

Bioassays can be expensive, both in terms of time and money. It is, therefore, sensible to consider bioassay optimisation: ways to design assays which minimise resource use while maximising... read more →

17th January 2024
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Why Weight? Response Weighting for Bioassays

A concept we’ve discussed several times over the years is that of homogeneity of variance. We highlight it so regularly as it’s among the most critical properties that relative... read more →

23rd April 2024
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Potency Assays for Cell and Gene Therapy: Statistical Challenges

At the forefront of medical development lies the world of cell and gene therapy. Unlike traditional, small molecule therapeutics, treatments based on biologics can treat, cure, or even prevent... read more →

14th May 2024
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Optimising Suitability Criteria for Bioassays

When running a bioassay, we face a constant battle between two competing requirements. The assay must be able to detect when something has gone wrong with the experiment or... read more →

4th June 2024
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ELISA Bioanalysis: Key Advantages of the BY Method

Enzyme-Linked Immunosorbent Assays (ELISA) are a key tool for determining concentrations, forming a key component of many fields in the life sciences. From testing food products for allergens to... read more →

27th June 2024
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What is the 5PL Formula?

In bioassay analyses, there are three statistical models that are commonly fit to dose-response data: the linear model, the 4PL model, and the 5PL model. We’ve examined the properties... read more →

6th August 2024
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Making the most of your bioassay control wells

The control: a vital part of any scientific experiment. The only way to establish causality between the dependent and independent variables in an experiment is by comparison with a... read more →

17th September 2024
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Using Statistical Process Control (SPC) for Bioassays

Bioassays serve as a method of testing a product: does the latest batch of our biologic have an acceptable potency? To do this effectively, we need to ensure that... read more →

1st October 2024
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Building your Bioassay I (with RoukenBio)

The bioassay development cycle can be a long and winding road, with vital decisions at every stage of the process. Choosing the wrong path can mean hours of wasted... read more →

28th October 2024
Building your Bioassay

Examining the Three-Parameter Logistic (3PL) curve for Bioassay Modelling

One of the most frequent topics of discussion on this blog has been the correct and optimal utilisation of different classes of statistical models with bioassay data. Most common... read more →

31st October 2024
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