Men and women are equally likely to finish a book – but men decide much faster than women if they like a story or not, according to analysis of reading habits by Jellybooks.

The start-up, which focuses on book discoverability and reader analytics, has tested hundreds of digital titles on hundreds of volunteer readers over the last few months. Working with many of the UK’s major publishers, it uses a piece of JavaScript in the ebooks to look at readers’ habits: when they pick up, complete or abandon a title. The test groups were made up of significantly more female volunteers, with a 20/80 male/female split.

Jellybooks found that the completion rate of a book was not at all gender-specific, regardless of whether a title was fiction or non-fiction. “In most cases, the likelihood that a reader will finish a book is not correlated with gender; both sexes have an equal probability of finishing a book”, wrote founder Andrew Rhomberg, on Digital Book World.

The “notable exception” to this rule, found Jellybooks, was for “books that deal with feelings”, whether these are feelings about grief or love, or books about relationships. “Books that predominantly deal with these categories show noticeable differences in completion rates, which can vary from relatively small … to very large difference, in which the completion rate for men is half the value or less than that for women,” revealed Rhomberg. “Not only do fewer men start reading these books, but those who do start reading them are more likely to give up on them than women are, irrespective of the quality of the content or the narrative.”

And while in general men and women finished books at an equal rate – Rhomberg used the example of a book by a Canadian author, tested on 400 readers and finished by 27% of men and 28% of women – Jellybooks did discover that “men decide much faster than women do if they like a book or not”.

“The initial decline during which most readers are lost is much sharper and earlier for men than it is for women, and this is a behaviour that we observe for the majority of books,” writes Rhomberg. “So put another way, men give up on a book much sooner than women do. Given the identical completion rates, we take this to mean that men either have more foresight in this regard or that women continue reading even if they already know that the book is not to their liking. We suspect the latter, but cannot prove it at this point.”

If an author wants to hold on to a male reader, they have “only 20 to 50 pages to capture their attention”, according to the research. “No room for rambling introductions,” Rhomberg told the Guardian. “The author needs to get to the point quickly, build suspense or otherwise capture the male reader, or he is gone, gone, gone.”

Age was a bigger factor in completion rates than gender, found Jellybooks, with readers under 35, and over 45, more likely to finish a book than those between the two ages, for the majority of books. Rhomberg speculates on Digital Book World that readers between the ages of 35 and 45 may be the “most time-pressed demographic”, with “little time for reading”.

But there are books that “sometimes significantly outperform in this particular age segment”, said Rhomberg: “Titles that deal with the complexities of adult life – from challenges at work and pursuing a career to the ups and downs of relationships and having a family.”

Genres covered by Jellybooks’ testing range from literary fiction to crime and travel, with publishers tending to place books in the trial before launch. “So if it’s a fairly big title, they can see if they should throw a marketing budget at it, or if it’s a smaller title which is resonating with an audience more strongly, which book should get the budget,” he said. “It’s a bit like audience testing for a movie. In the old days, the advance was proportional to the attention a book would get from a publisher, but now, that’s changing.”

Rhomberg does not believe publishers will use the reading analysis to change the contents of a book to suit ages or genders. “We don’t expect this to happen,” he said. “We can sometimes point at a particular chapter which seems to be more difficult … but in fiction, we can’t see enough detail [about why], and this is such a loaded topic … You don’t save a book by rewriting one scene, or changing a character. We don’t see that as being the idea.”