A Guardian analysis of push alerts for nine of the biggest UK news apps shows that, on balance, notifications about the Conservative party tend to be positive, while notifications about Labour are overwhelmingly negative.

While most of the providers showed a tendency to view the Conservatives more positively, the outcome was skewed by the Telegraph, which sent strongly pro-Tory and anti-Labour alerts.

For the millions of British voters who have news apps installed on their smartphones, push notifications are an important source of information about politics. While some recipients will tap on the pings and buzzes to read full stories, the majority of push alerts are never acted upon. That means the one-line summaries of the day’s breaking news events are frequently all readers get, giving them an enormous amount of power to shape perceptions.

The Guardian downloaded every UK-specific news app in the top 40 on the iOS App Store, and enabled the default notifications for each, from 6 November until 11 December, the day before the election.

Following a methodology applied by Loughborough University to analyse print news, the Guardian tracked every push notification in that period, and evaluated whether they were positive or negative for each of the three largest parties.

There were a net 18 positive push notifications for the Conservative party in the period since 6 November, and a net two negative for the Liberal Democrats. For the Labour party, however, there were a net 57 negative.

But the distributions were not the same for every publication. BBC News largely avoided notifications with clear winners, sending a net of one negative story about Labour and an even breakdown of stories about the Conservatives. Similarly with the Guardian (evens for Labour and net two negative for the Conservatives) and Sky News (net five negative for Labour and net three negative for the Conservatives).

The Mirror expressed clear support for Labour through its choice of which stories to send notifications for, and how to phrase them: a net three positive for Labour and net three negative for the Conservatives, with neither party receiving a single story to counterweight the general impression. The Mail was roughly as skewed in the other direction, with four negative stories about Labour and a net of zero about the Conservatives, and the Express was stronger, with eight stories attacking Labour, and a net of four supporting the Conservatives.

Skewing everything, however, is the Telegraph. The paper sent out 40 push alerts that were negative for Labour, without a single positive story, and a net of 18 that were positive for the Conservatives. The paper’s practice of pushing most opinion columns contributed substantially to the skew, but even with those excluded, notifications such as “‘Reckless’ Labour to send public debt soaring with £600bn borrowing spree” and “Corbyn will betray Brexit, Johnson says as he takes election fight to Labour heartlands” left readers in no doubt as to who the publication supported.

Even without the Telegraph included in the count, however, the Tories received a net zero positive pushes from all the other publications the Guardian tracked, while Labour received -17.

A few specific events stand out in the analysis. On 6 and 7 November there was a run of bad notifications for Labour, around Tom Watson’s resignation, Ian Austin’s intervention, and no less than five hits from the Telegraph in one 24-hour period. Conversely, the one-sided election pact announced a few days later by the Brexit party saw a run of positive notifications for the Conservative party, with the Express specifically noting that Corbyn was “facing wipeout”.

One common concern about push notifications is the lack of any norms around mistakes. Both the Express and Daily Mail pushed out the claim that, in the Mail’s phrasing: “Labour activist ‘PUNCHES Matt Hancock’s adviser at Leeds hospital’”. In fact, no such punch was thrown, and video released less than an hour later showed the adviser walking into a protester’s arm. But neither publication sent a follow-up noting the error, and for any user who did not seek out extra news, the initial push may be the only claim they heard on the matter.

Some notifications were harder to categorise than others. A straight report of Labour’s broadband policy from the BBC (“Labour promises free broadband for all by part-nationalising BT and paid for by tech firm taxes, if it wins election”) was widely seen as a positive push from the news service that could help the party’s electoral chances. But a straight report from the Telegraph of a different Labour policy – “Labour vows to tax second homes as Corbyn launches manifesto” – was probably received rather less positively by a substantial chunk of the app’s users.

In early December, Guardian research revealed for the first time how smartphone users consumed election news. The findings were concerning for many, with some of the profiled users reading no news articles at all, instead gaining the entirety of their understanding from headlines seen on social media, push alerts, and other snippets.