An increase of 100 percent can cover the fact that something increases from 1 to 2.
Avoid exaggerations or misinformation: Always state what a percentage covers in absolute numbers.
In 2015, an alarming telegram from the Danish news agency Ritzau was shared by several news outlets.
The story was about a study that found more brain tumours among women who use birth control pills or other hormonal contraception than among women who do not.
The risk of brain tumours is 90 percent higher among birth control pill users, the study concluded. Wouldn’t that make some women consider dropping the birth control pills?
Only further into the article, the reader was told that the risk of getting a cancerous tumour in the brain was in fact extremely low. Only 5 out of 100,000 women of childbearing age are affected per year. That is, the risk of getting a brain tumour is already only 0.01 percent.
If the risk for women on birth control pills increases by 90 percent, it increases to 0.019 percent — still a very low risk. But the Ritzau story did not reveal that.
In fact, so few Danish women get brain cancer that the data set is not large enough to assess whether birth control pills actually increase the risk, we wrote on Videnskab.dk. A more balanced version of the story also made its way to Time and The Guardian.
\ Download the guide
This article is part of the guide 11 tips for journalists: How to avoid blunders when reporting on science. The guide is accessible in three formats:
Online articles regarding each of the 11 tips.
The full guide of 11 tips as a PDF-file.
The 11 tips as a checklist, a one-pager.
Not uncommon to exaggerate
The brain tumour story is an example of misinformation about the risks of a drug that thousands of women use.
But it is not uncommon for journalists to exaggerate risks and effects when throwing themselves at research based on numbers and statistics.
The blunder usually occurs because the journalist confuses relative numbers with absolute numbers.
Relative numbers (or values) are dependent on other numbers. They typically show an increase or a decrease in percentage.
In the example of birth control pills and brain tumours, the relative risk increase is 90 percent. The number indicates how big the difference is between the number of brain tumours in women who take birth control pills and women who do not.
Great potential risks
Absolute numbers (or values) indicate how great the risk of brain tumours in birth control pill users is when you take into account how few women actually get brain cancer.
Contrary to the relative number, the absolute number gives the individual contraceptive pill user an impression of how low her risk of getting a brain tumour is.
You can create unnecessary fear and give a misleading picture of how high risk an effect really is if you state only the relative numbers.
Another example: you report in a news story that the risk of a plane crash has increased by 100 percent. But you fail to explain that 100 percent covers a single year in which there was one plane crash out of 3 million flights, while the next there were two. This provokes unfounded fear of flying.
The absolute figures are not always included in the press release, nor in the scientific article, so ask the scientist for them. Ask what the relative numbers actually cover and how high the risk is for the individual, no matter what topic you are writing about.
Read more tips by clicking the blinking icons at the left in the graphic below.
\ About the Science Journalism Guide
This guide is for journalists and journalism students who are working on science and research news.
It provides 11 specific tips on how to avoid common pitfalls when covering science material.
The guide is written by journalists at the leading Danish popular science site Videnskab.dk.
It summarizes our many years of experience and the best solutions for communicating research and science critically and nuanced and with credibility.
Help us learn
The guide is based on our own experiences as journalists at Videnskab.dk, and we have received feedback and input from several talented scientists, communicators and journalism students.
It is important to emphasize that the guide sets out only general guidelines and rules of thumb.
No two stories are alike, and you will probably come across science stories where the guide is lacking or where it doesn’t make sense to follow all the tips. In other words, the 11 tips in the booklet are not set in stone.
If you have ideas or suggestions for how our guide — or our journalism at Videnskab.dk — can be improved, we would always like to hear from you. If you have questions, or if you are interested in a presentation on science journalism from Videnskab.dk, you are also welcome to contact us. You can write to us at redaktion@videnskab.dk.
The guide has been compiled by
Lise Brix, Ditte Svane-Knudsen, Anne Ringgaard, Thomas Hoffmann, Frederik Guy Hoff Sonne og Marie Barse.
Editing and layout: Jonas Salomonsen og Jon Mathorne.
Illustrations: Thøger Junker.
Translation: Stephanie Lammers-Clark. Proofread by Randy B. Hecht.
©Copyright and publisher: Videnskab.dk.
Thanks for help, input and feedback
Videnskab.dk has recieved economic support for our work with developing and sharing knowledge about science journalism from Den Fynske Bladfond, a foundation that supports free press in Denmark.
The following has provided valuable input and feedback:
Claus Emmeche (Associate Professor), Eske Willerslev (Professor), Felix Riede (Professor, AU), Gunver Lystbæk Vestergård (PhD in science journalism), Jesper Lesager Christensen (Journalism Student), Karin Frei (Professor), Kresten Roland Johansen (Lecturer, science journalism), Kristian Hvidtfelt Nielsen (Associate Professor,), Lasse Laustsen (Associate Professor), Mads Faurschou Knudsen (Associate Professor), Maja Horst (Professor), Mikkel Gerken (Professor), Oluf Danielsen (External Lecturer), Peter Hyldgård (Chairman, Danish Science Journalists), Simon Taarnskov Aabech (Journalism Student), Søren Kjørup (Philosopher, Emeritus), Andreas Søndergaard Petersen (Journalist, TjekDet) as well as journalism students at Roskilde University and Danish School of Media and Journalism.
