Systematic reviews and meta-analyses are valuable evidence reports that get outdated when new studies become available. Keeping track of the literature is warranted but time-consuming. There is an alternative that works well for many updates.

What are the chances that researchers of a new study don’t cite the original review or any of the studies included? It’s possible, but it’s reasonable to expect that the better studies cite relevant previous studies. It’s just a lot of work to track all citations to all articles. Until now.

CoCites extracts the citations and reference lists of many articles at once and is…


Edwin Torres from USA, CC BY 2.0, via Wikimedia Commons

2020 was a good year for Alzheimer’s blood tests. Many new tests, all different biomarkers, and all accurately predicting Alzheimer’s. Have you ever wondered how that is possible? How different biomarkers can all accurately predict a disease that is so complex? The answer is short and sobering: they can’t. Too often, the studies behind the tests don’t support the claims.

2021 is only one week old, and researchers have already come up with another blood test. “We can now very accurately predict the risk of developing clinical Alzheimer’s disease in the future, with a simple blood test on symptom-free individuals…


Photo by Celpax on Unsplash

Eerder deze maand schreef ik een column in NRC over opiniepanels waarvoor deelnemers zich zelf aanmelden en enquêtes die via social media verspreid worden. ‘Waardeloze enquêtes’ was de kop.

Opinieonderzoek is ‘waardevol, niet waardeloos’, schreven de adviseurs van het EenVandaag Opiniepanel, de hoogleraren Bethlehem, Van der Meer en Van Holsteyn, in een ingezonden brief (volledige versie).

Waardeloos en waardevol. Onze conclusies staan lijnrecht tegenover elkaar, maar over de feiten zijn we het verrassend eens. Hier zijn alle punten op een rijtje.

Niet representatief

We zijn het eens dat onderzoek met zelf-aangemelde deelnemers geen representatieve resultaten oplevert. Representatieve resultaten krijg je…


A radically different search method

The default method to searching scientific literature is entering keywords in a literature database. The quality and relevance of the keywords determines the quality and relevance of the results. Entering several best-guess keywords will return relevant articles, but they are likely not all there is and may not be a ‘representative’ selection. Researchers who don’t want to miss any relevant studies write extensive search queries for multiple literature databases that may catch all relevant articles and many others. Our preferred strategy is rather inefficient.

CoCites searches the scientific literature radically differently. The tool finds related…


A new study shows that people who drink alcohol at home tend to drink more during the coronavirus crisis. Newsweek mentions that “1 in 3 Americans said they had consumed alcohol at harmful “binge drinking” levels during the coronavirus pandemic,” but cautions that the data was self-reported.

Photo by Mikhail Tyrsyna on Unsplash

1 in 3?

Self-report data means that the researchers asked participants, for example, “how many glasses of alcohol do you drink per week?” without checking whether the answer is correct. Self-report data is common in scientific research as it is merely undoable to verify all study data. …


Photo by Bima Rahmanda on Unsplash

When I attend lectures online from home, I easily get distracted. Only occasionally, I can blame the presenter. At home, there are too many distractions and, apparently, not enough incentives to ignore them.

The biggest distractions are just one mouse click away. Like a quick look-up on the internet or some administrative chore that I think I can do while staying engaged, but that I cannot really. Asking questions gets harder as soon as I am no longer sure that the presenter hasn’t already said what I missed.

Online, I can avoid embarrassing questions easily as others in the audience…


When I read news articles about health research, I often wonder what I would have understood if I weren’t an epidemiologist.

I bet it would be similar to reading about topics I know nothing about, like mortgages, hip hop, and string theory.

I would easily believe that what I read is true, especially if the study is large, from a respected university, and published in a respected scientific journal. Written in a respected newspaper. Respected by my own standards, that is.

I imagine that the statistics would read like temperatures in Fahrenheit when Celsius is your scale. I may have…


New York Times, September 11, 2018

Reading the news is a great way to follow what happens in the world, but the stories aren’t neutral and accurate. How to critically digest the news is a valuable skill that can be taught, and that is developed through practice. That is what my class Critiquing Health News is about.

During this spring semester, 30 students of Emory College discussed media articles about scientific studies on health and disease, one each week. They explored the science behind it and compared the science with the news. We discussed each reporting from a new perspective or with a different focus.

As…


Photo by Markus Spiske on Unsplash

I have muted the words “coronavirus” and “Covid-19” on Twitter. I hardly see any tweets about the coronavirus epidemic anymore. I would like to stay informed but felt that Twitter was no longer the right medium for that. The line between knowledge and opinion had blurred. I could no longer judge which information I should trust and which I shouldn’t. One scientist tweets that the number of infections is increasing exponentially, the other writes it isn’t. One thinks government measures are going too far, the other not far enough. All experts, but not in this area.

My class on critical…


Photo by chuttersnap on Unsplash

The media response to the controversial genetic study of sexual orientation had barely died down when the renowned journal Nature Communications published a new study about the genetic influence on income. This was another large-scale analysis using data from the same British UK Biobank, 285,000 participants this time, with similar unsurprising results: DNA also has a minimal impact on income differences.

I often don’t understand why mega-studies receive so much attention. Large studies may seem credible, but their credibility is not self-evident. Studies with tens or hundreds of thousands of participants, such as the UK Biobank and the US Framingham…

Cecile Janssens

Professor of epidemiology | Emory University, Atlanta USA | Writes about (genetic) prediction, critical thinking, evidence, and lack thereof.

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