How Useful Is Nutritional Epidemiology?

Nutritional epidemiological findings are often the studies that generate the most buzz, but they’re also the ones that get harshly criticized. Some folks will even go out of their way to say that the entire field produces findings that are mostly useless. Here’s what one of the leading meta researchers has to say about nutritional epidemiology: “Nutritional Epidemiology is a scandal. It should just go to the waste bin. Read More

False Positives, FWER, and FDR Explained

If you torture your data long enough, they will tell you whatever you want to hear - Mills (1993) False positives via statistical hypothesis testing are a severe problem in the scientific literature (Ioannidis, 2005). If a statistically significant finding looks real, but it’s not, and we make policy or clinical decisions based on this finding, it can have catastrophic consequences. Unfortunately, many researchers are still unaware exactly why false positives are so prevalent in the scientific literature, so, I’ve decided to explain some of the common reasons for the high prevalence. Read More

Meta-Analysis: Choose Your Model Wisely

Why Do a Meta-Analysis? Meta-Analyses are statistical techniques where we take the treatment effects from several studies and pool them to estimate the overall treatment effect. This type of analysis is conducted so that we can get a precise estimate of the true treatment effect or estimate the mean of several true treatment effects and to notice how robust the effects are across studies. If the individual study treatment effects tend to vary substantially across the studies (true heterogeneity, separated from random error), then we want to explore the sources of this observed dispersion. Read More

Myth: Covariates Need to Be Balanced in RCTs

Before I get into the nitty-gritty, I want to remind everyone why we randomize in the first place. It’s to reduce selection bias and to get rid of systematic variation amongst groups, which allows us to come to more precise and efficient causal inferences. Many critics claim that we can’t make valid causal inferences if there’s an imbalance in covariates between the groups. Here’s an example. Say, hypothetically, we had two groups, and we wanted to see the effect of a statin on all-cause mortality and compare it to placebo. Read More

Four Misconceptions About Statistical Power

Statistical power, within the context of hypothesis testing, is the probability of rejecting the test hypothesis at a specified level, given that the alternative hypothesis is true. In simpler words, it’s the probability of finding a statistically significant effect, when there is one. Here, I address some misconceptions I often see about statistical power. Misconception: Statistical power can only be increased with larger sample sizes Truth: Nope. Here are some other things that increase statistical power: Read More

The Story of Antidepressants and Bad Journalism

Setting the Narrative Nearly a decade ago, a researcher by the name of Irving Kirsch conducted one of the most extensive studies on antidepressants. He compiled the published clinical trial data on antidepressants, and to make sure that he wasn’t analyzing data that only supported antidepressant effectiveness, he also invoked the Freedom of Information Act and dug up all the unpublished pharmaceutical data. Before starting this ambitious project, Kirsch, a medical researcher at Harvard, was the man who spearheaded most of the research behind the placebo effect. Read More

It's Looking Bad for Fish Oil and CVD

Fish oil supplements and cardiovascular disease have had a long and controversial history. There was a lot of inconsistency in the research around supplementation and several organizations only added to this confusion. The incomplete reporting by media outlets have also confused the public. Here, I’ll give a brief timeline of the evidence for fish oil and CVD outcomes. 1970s | A group of explorers noticed that people who consumed fish also had lower incidences of heart disease. Read More

Prescript Assist Is a Risky Supplement

What is Prescript Assist? Prescript Assist is a popular probiotic supplement in the ancestral health community because it is marketed as following ancestral principles. The claim is that this product contains microorganisms found in soil, which are “natural” and what our ancestors consumed with their unwashed produce. Some of the claims of this product are the following: It can survive the harsh conditions of the gastrointestinal tract It can colonize the gut Read More

Do Probiotics Have Any Clinical Evidence?

A lot of health products that you’ll end up buying won’t have the evidence to back up the claims listed on the product. Probiotics are one of these supplements. Approximately 3 million adults in the U.S were estimated to take probiotics back in 2012. That number has probably increased significantly by now. Especially when research on the effects of the microbiome in various health outcomes has entered the mainstream media. Read More

How Did We Figure Out Smoking Causes Lung Cancer?

Proving a cause and effect relationship isn’t easy. Causality is a complex subject, and there are thousands of texts on it, involving philosophical and mathematical arguments that are beyond my understanding. However, I do understand a bit of causality to discuss how we arrive at cause and effect relationships in the sciences. One of the first things often drilled into students in a research methods course is that correlation does not equal causation. Read More