For a political culture awash with polls and punditry, the mock convention at Washington and Lee University offers one of the most meticulous and intriguing predictions of its kind, having successfully forecast the nominee of the party not in the White House in 19 of 25 attempts, including all but two since 1948…

In the end, Mr. Trump earned 1,320 delegates, Mr. Cruz 652 and Senator Marco Rubio of Florida 399. No other candidate topped 100 delegates.

The prediction is a serious matter on this history-soaked campus, where students have hosted a mock convention every four years since 1908. Designed to predict the nominee of the party not currently in the White House, it draws alumni and prominent politicians from around the country, engages students in a four-year planning and fund-raising effort, and has historically precipitated more than a fair share of celebratory parties, as well as an annual parade.

“I’ve told the students, and I honestly believe this: On Saturday, they will be in a better position to determine the Republican nominee than anyone else in the country,” William F. Connelly Jr., a congressional scholar here who has advised the convention since the early 1990s, said on Tuesday.