The study also looked at the combined print and online reading times across 12 national newspapers, which was found to have fallen by an average of four per cent each year, from 2007 to 2011.
Individually, online reading time increased, Neil Thurman, the study's author and senior lecturer in electronic publishing at City University, told Journalism.co.uk, but not enough to offset decreases in print.
The study, titled Newspaper Consumption in the Digital Age, looked at "time spent reading" data for the titles but did not include data from apps.
There is a large disparity between the relative success of individual titles, however. The data, taken from the National Readership Survey, Audit Bureau of Circulation and Nielsen's internet activity tracking software, showed that titles in listed as "popular/tabloid" were least successful in translating their print popularity into time spent reading online, while the "quality/broadsheet" titles were more successful.
"The most successful brand has been the Guardian and they were the only brand that managed to increase their time spent reading across the four years," Thurman said. "It was only by about 1 per cent, excluding apps again, but they've been the most successful."
The metric of "time spent reading" was chosen, Thurman said, because it represented a clearer and more comparable measurement for print and online audience data than unique users or page impressions.
"It tells you about engagement and about attention and that correlates quite well with the income that people can get via advertising," he said. "Time is obviously important when it comes to selling advertising because if readers are paying attention and putting time into a brand then that's something that will enable you to sell more advertising."
The study looked at time-spent-reading data for 12 newspaper titles across the UK: five "popular/tabloid" titles in The Sun, The People, the Daily Mirror, the Daily Star and the Daily Record; two "middle market" titles in the Daily Mail and the Daily Express; and five "quality/broadsheet" titles in The Independent, The Guardian, The Daily Telegraph, The Times and The Financial Times.
Data regarding time spent reading on the titles' apps was omitted from the study. Although Thurman felt it would be an important statistical addition, the only available data was regarding page impressions, which he felt would not accurately compare with time spent reading.
"The app data only became available very late, from only a few newspapers, it's still unreliable and it doesn't give you anything about time spent reading which is why we didn't include it."
At the WAN-IFRA World Editors Forum in June, a report on the World Press Trends survey suggested that "news engagement via tablet, as measured by time spent with news content, is equal to that of the printed newspaper" based on data from the United States, Germany and France.