The Safety Population is used for the analysis of safety, including adverse events, toxicity and laboratory evaluations. A patient should be included if, and only if, they actually received a study treatment (even if it is a placebo). This set of patients are grouped for analysis according to the treatment they actually received, as opposed…
We have previously discussed the 4 parameter logistic (4PL) model. Sometimes you may see slightly different versions of the 4PL equation – these are all mathematically equivalent. However, one thing to watch out for is that the meanings of the four parameters can vary between these versions. If you’re fitting a 4PL and getting parameter…
Recently our team at Quantics were working on an analysis for an ecotoxicology client which called for us to use the Jonckheere-Terpstra test for ordered differences which is recommended by the OECD in their guidance document on statistical analysis of ecotoxicity data. We were subsequently asked to explain how it was used and we thought…
This 3rd clinical trial design blog from Quantics Biostatistics takes an introductory look at how the various types of clinical endpoints (introduced in our previous blog) determine the recommended calculations for what can be inferred from summary data. Formal statistical testing for a clinical trial is traditionally based on the concept of proof by contradiction….
Our recent paper, Estimation of Relative Potency from Bioassay Data that Include Values below the Limit of Quantitation (Francis Bursa, Kelly J. Fleetwood, Karie J. Hirst and Ann Yellowlees), discusses values below the limit of quantitation (“LOQs” – sometimes called “non-reportables”) which are a common issue with bioassay data, and specifically how to deal with…
In ecotoxicology statistics there are three main types of data: Continuous data can take any numerical value over a range (e.g. weight), while discrete data take a finite number of values (e.g. colour). Quantal data, the focus of this post, can take only one of two values (e.g. alive/dead or mobile/immobile) and are often recorded…
In our last blog we discussed sample size choice and identified the key information that your statistician needs to know and why. In this second clinical trial design blog, we look at the different types of endpoints in clinical trials and some of the statistical issues they raise. Read our blog on sample size choice…
Previously, we discussed the definition of relative potency and how it relates to biological similarity, and therefore the need for parallelism between reference and test dose–response curves. In order to test for parallelism and calculate a relative potency, the assay data must be mathematically modelled. From a modelling perspective there are two fundamentally different types…
Like all statistical analyses, network meta-analysis relies on a specific set of assumptions. Here, we’ll look at the key assumptions of network meta-analysis. In order to draw valid conclusions about the relative efficacy and safety of treatments in a network meta-analysis and facilitate good decision making, it is important to understand and evaluate these assumptions….
Ecotoxicity tests are experiments performed to evaluate the toxicity of a test substance in order to predict the effect on natural populations. There are many different types of test, but the general principle is that organisms are exposed to different concentrations or doses of a test substance, with at least one control group that is…
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 (usually) know the potency of the reference sample, this gives us a measure of the potency of the test sample by comparing it to that reference….
Welcome to Quantics’ Clinical blog. This blog will explore some of the statistical aspects of clinical trial design including study design, sample size, data management and analysis planning. The aims of this blog are not only to provide thought provoking insight into some of the latest statistical developments for clinical trials but also to create…
Find out about our network meta analysis services Welcome to Quantics’ health technology assessment blog. This blog will explore some of the statistical aspects of health technology assessment, including meta-analysis, network meta-analysis and survival analysis. The aims of this blog are two-fold. Firstly, we want to create a knowledge base to help those who are…