After several months without contributing for Visualoop, I’m back. Although I missed being an active writer here, writing my PhD thesis was a very demanding process and left me with little time for other activities. Now that I finished writing the thesis, and although I still have to defend it, I must say I’m a little relieved.
After spending so many months in this endeavor, I think I should explain what the investigation was about. Essentially I studied the use of mathematics in Portuguese newspapers.
The bad use of mathematics in the news is a problem for which several authors have drawn their attention to. Among others, Allen Paulos, in his book A Mathematician Reads the Newspaper explores several misuses of maths in the news, as well the reason why they occur. He also highlights that not only is mathematics not properly used in the news, but also that it is essential to the journalists’ work.
This last point – it is important to use mathematics in the news – is also highlighted by Victor Cohen and Lewis Cope in their book News & Numbers , where they analyse frequent examples of poor use of mathematical information in health news.
To this knowledge field it is important the contribution of Prabu ,who in 1992 carried out a study in which he concluded that the majority of the figures in the news (although he only studied a small set of graphs) distorted the numerical data in which those were based on.
Although there are systematic studies on the use of mathematics in the news and the errors that occur in this context — by Maier and Brand — there is a large gap of information referring to what happens in most countries. So, the investigation conducted during my PhD aims to be a contribution to understand the reality of the Portuguese newspapers with regard to frequency and misuse of mathematical information in the newspapers and also to understand the reasons why there exist mathematical errors, in case they are identified.
The results revealed that mathematics is scarcely used in the news, although journalists recognize it is more used today than some decades ago. It is also noted that the usefulness of mathematics is recognized in Portuguese newsrooms, not only as a means of describing, deepen or legitimate news, but also as a means to create worthy news story, through the use of databases.
We also concluded there is a poor use of numbers and graphs, which are explained by several causes such as the deficit of mathematical competences, the lack of critical thinking about numbers, the shortness of time or poor revision and control over the mathematical information that exists in the news.
Focusing on the errors in graphics, I’ll describe to you some examples that make the subject more tangible:
Source: Expresso (printed version), published on 29.03.2013
Errors: 1 – There is no uniformity between intervals in the horizontal axis (xx); Consider the two graphs on the left: the total amount of money which the circular graph refers to is 1,49 (0,57+0,12+0,11+0,69) and not 1,50 as it is pointed on the graph further to the left.
Source: Jornal de Notícias (printed edition), published on 09.02.2013
Error: The time (in years) on the horizontal axis is shown using intervals of five years, except for the last interval, which refers to seven years (2000 to 2007), but the line segment refering to the seven year range has the same length as the ones refering to a range of 5 years.
Source: Dinheiro Vivo, supplement of Jornal de Notícias (online version), published on 12.06.2013
Error: 1,36€ is marked below 1,30€ relative to the vertical axis (yy).
I hope this was interesting for you. If you want further information feel free to contact me.
 Paulos, J. A. (1995). A mathematician reads the newspaper. Nova Iorque, Anchor Books.
 Cohen, V. and L. Cope (2001). News & Numbers, Iowa State Press.
 Prabu, D. (1992). “Accuracy of Visual Perception of Quantitative Graphics: An Exploratory Study.” Journalism & Mass Communication Quarterly 69(2): 273-292.
 Maier, S. R. (2000). Newsroom numeracy : a case study of journalistic use and misuse of numbers in the news. School of Journalism and Mass Communication. Chapel Hill, University of North Carolina. PhD Thesis.
 Maier, S. R. (2002). “Numbers in the news: a mathematics audit of a daily newspaper.” Journalism Studies 3(4): 507-519.
 Brand, R. (2006). Suckers for Numbers. Rhodes Journalism Review. 26: 26-27.