What is the -2LL or the Log-likelihood Ratio?

If you have ever read the literature on pharmacokinetic modeling and simulation, you are likely to have run across the phrase  “-2LL” or “log-likelihood ratio”. These are statistical terms that are used when comparing two possible models. In this post, I hope to explain with the log-likelihood ratio is, how to use it, and what … Continued

Prediction of Overall Survival or Progression Free Survival by Disease Control Rate at Week 8 Is Independent of Ethnicity: Western Versus Chinese Patients with First-line Non-small Cell Lung Cancer Treated with Chemotherapy with or without Bevacizumab

Categorizations of best response observed at week 8 of first-line treatment in two studies of bevacizumab plus chemotherapy in Western and Chinese patients with non-small cell lung cancer were assessed together with baseline prognostic factors in multivariate parametric models to predict overall survival and progression free survival.

Certara Partners With Thomson Reuters to Expand Data Access Through Its D360 Platform

Certara customers will now be able to view curated life sciences content from Thomson Reuters Cortellis™ alongside their proprietary scientific data ST. LOUIS, MO – October 22, 2013 – Certara™, a leading provider of software and scientific consulting services to improve productivity and decision-making from drug discovery through drug development, today announced that it is … Continued

Boehringer Ingelheim Selects Certara’s D360 as its Global Drug Discovery Platform

D360™ will permit chemical structure and related biological property data to be shared between global sites. ST. LOUIS, MO – Oct. 17, 2013 – Certara™, a leading provider of software and scientific consulting services to improve productivity and decision-making from drug discovery through drug development, today announced that the pharmaceutical company Boehringer Ingelheim has chosen … Continued

Using Sampling “Windows” for PK Blood Samples

One of the most common questions posed by clinical operations experts when including pharmacokinetic sampling in a clinical trial is the following: “What is the time window we should allow for each blood sample?” My answer is always the same: “Don’t include any window.” I am almost always met with a confused look. The confusion is … Continued

What is “Adjusted” r-squared?

Linear regression is a common tool that the pharmacokineticist uses to calculate elimination rate constants. Standard linear regression provides estimates for the slope, intercept, and r2, a statistic that helps define goodness of fit. Statistical texts define r2 as the coefficient of determination and it is calculated using the following equation: where SS = the sum of … Continued

Demystifying CDISC, SDTM, and ADaM

Team discussions regarding CDISC often bring in the mists of darkness, which obscure the landscape and prevent us from moving in a clear direction. Then if we weren’t confused enough, the discussion moves to SDTM, ADaM, and clinical databases, and we feel like we are spinning out of control. The land of clinical study data can … Continued