Truth decayUncertainty about Facts Can Be Reported Without Damaging Public Trust in News: Study

Published 31 March 2020

The numbers that drive headlines – those on Covid-19 infections, for example – contain significant levels of uncertainty: assumptions, limitations, extrapolations, and so on. Experts and journalists have long assumed that revealing the ‘noise’ inherent in data confuses audiences and undermines trust. A series of experiments – including one on the BBC News website – finds the use of numerical ranges in news reports helps us grasp the uncertainty of stats while maintaining trust in data and its sources.

The numbers that drive headlines – those on Covid-19 infections, for example – contain significant levels of uncertainty: assumptions, limitations, extrapolations, and so on.

Experts and journalists have long assumed that revealing the ‘noise’ inherent in data confuses audiences and undermines trust, say University of Cambridge researchers, despite this being little studied.

Now, new research has found that uncertainty around key facts and figures can be communicated in a way that maintains public trust in information and its source, even on contentious issues such as immigration and climate change.

Researchers say they hope the work, funded by the Nuffield Foundation, will encourage scientists and media to be bolder in reporting statistical uncertainties.

“Estimated numbers with major uncertainties get reported as absolutes,” said Dr Anne Marthe van der Bles, who led the new study while at Cambridge’s Winton Centre for Risk and Evidence Communication.

“This can affect how the public views risk and human expertise, and it may produce negative sentiment if people end up feeling misled,” she said.

Co-author Sander van der Linden, director of the Cambridge Social Decision-Making Lab, said: “Increasing accuracy when reporting a number by including an indication of its uncertainty provides the public with better information. In an era of fake news that might help foster trust.”

The team of psychologists and mathematicians set out to see if they could get people much closer to the statistical ‘truth’ in a news-style online report without denting perceived trustworthiness.     

Cambridge says that they conducted five experiments involving a total of 5,780 participants, including a unique field experiment hosted by BBC News online, which displayed the uncertainty around a headline figure in different ways.

The researchers got the best results when a figure was flagged as an estimate, and accompanied by the numerical range from which it had been derived, for example: ‘…the unemployment rate rose to an estimated 3.9 percent (between 3.7 percent–4.1 percent)’.  

This format saw a marked increase in the feeling and understanding that the data held uncertainty, but little to no negative effect on levels of trust in the data itself, those who provided it (e.g. civil servants) or those reporting it (e.g. journalists).

“We hope these results help to reassure all communicators of facts and science that they can be more open and transparent about the limits of human knowledge,” said co-author Prof Sir David Spiegelhalter, Chair of the Winton Centre at the University of Cambridge.