Not what you think it does! — Everyone keeps talking about covid becoming endemic, but as I listen to the conversation, it’s becoming more & more clear to me that very few of you know what “endemic” means. So here’s a thread on how pandemics end. In the beginning of any pandemic, we have 4 options for…

The CDC’s recent announcement that the Delta variant has an average reproductive number of 6–9 has a lot of people concerned & many are asking me about whether this means we need COVID boosters. Let’s talk through the math of how we might decide! First, we need to make sure…

Infectious diseases are a community problem, not an individual problem, and we all need to work together to bring them under control. Right now, that means working together to stop the spread of the new coronavirus which is causing COVID. …

A randomized trial explainer — Have you heard that adherence adjustment in randomized clinical trials never works? That’s not true! But many adherence-adjusted analyses fail because the researchers use the wrong methods. Read on to see the evidence for and against estimating adherence adjusted effects in randomized trial, and learn how modern causal inference tools…

A causal inference explainer — If you are interested in understanding causal effects from data, then you need to understand the concept of positivity. This article explains what this means and why it’s important. First, what it’s not: the type of positivity I’m going to talk about is not a positive mental attitude! The technical…

An epidemiology teaching resource — When epidemiologists teach precision & accuracy, they often use images of a target, like these from the Wikipedia article. This is a great analogy for accuracy and precision. And it also makes a great analogy for thinking about the relationship between your estimate and your target effect (or estimand). …

A causal inference explainer — We all love French fries, but recently a Harvard professor made headlines with the claim that we should only eat 6 fries per serving. Less is more is generally good advice when it comes to any food, but why is 6 fries the magic number? Why not 5 or 7…

A cartoon causal inference book review — If you’re interested in causal inference, you’ve probably wondered at one time or another what even is a cause? The answer to that is complicated, because it’s not really science — it’s philosophy. And even philosophers aren’t sure. But if you want to get some background on how philosophers think…