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 →
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Bioassay Blog
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 →
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 →
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 →
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 →
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 →
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 →
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 →
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 →
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 →
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 →
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 →
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 →
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 →
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 →
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 →
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 →
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 →
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 →
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 →
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 →
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 →
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 →
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 →
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 →
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 →
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 →
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 →
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 →
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 →
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 →
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 →
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 →
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 →
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 →
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 →
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 →
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 →