From The Telegraph:

[Agatha Christie’s] whodunit murder mysteries have confounded millions of armchair detectives, leading them through a literary maze of twists and turns before a super sleuth finally unmasks the culprit.

A panel of experts analysed 26 of the author’s most famous books, including Death on the Nile, Murder on the Orient Express and The Murder of Roger Ackroyd, concluding that certain plot structures could help the reader identify the killer some time before he or she is dramatically revealed.

They said that if there were several land vehicles in the story, the killer was likely to be female. Similarly, a prevalence of nautical vehicles suggests they are more likely to be male.

The panel also found that the structure of a Christie novel could be reduced to a list of key events: the body will be found early on, a closed group of will be presented to the reader, the detective will then be introduced and a series of red herrings will follow and finally, after it is solved, the story will be wrapped up quickly and efficiently, leaving the reader satisfied.

Link to the rest at The Telegraph