Sacking by numbers

Vialli: The maths say he should have stayed

Football managers should be fired or spared according to the results of a mathematical equation, a Cambridge University researcher says.

Chris Hope from the Judge Institute of Management says his equation could help under-pressure club chairmen make up their minds on the future of the team boss.

I'm a fan of Cambridge United, so I've seen good managers and poor managers in my time

Dr Chris Hope

"It would probably be worth their while to spend a few minutes just plugging some figures into this equation... and they might find the performance is not as bad as they thought it was," he told BBC Radio 5Live.

Dr Hope's equation shows John Gregory should have been dropped by Aston Villa in December 1999 - a full two years before he finally left the club.

The model also suggests Chelsea were wrong to sack Gianluca Vialli - he had not done as badly in the job as his critics said.

Dr Hope said his equation worked by taking into account the number of points per game scored by a team, with most weight given to the most recent games.

Honeymoon period

"After a certain honeymoon period, if that number of points per game falls below a certain trapdoor level, then it's time for the manager to go," he explained.

Dr Hope calibrated his model using data from the last six English Premiership seasons.

The best strategy, he said, was to give managers only a short honeymoon period of eight games, to put 47% of the weight on the last five games, and to sack managers once their club started scoring less than 0.74 points a game.

"A club adopting this strategy would obtain on average 56.8 points per season, compared with a Premiership average of 51.8 points.

"It would employ an average of 5.7 managers every 10 seasons, against the Premiership average of 4.5 managers.

"It would have sacked John Gregory at Aston Villa and Walter Smith at Everton, but not Ruud Gullit or Gianluca Vialli at Chelsea, nor Joe Royle at Everton, just," Dr Hope wrote in his research paper.

"I'm a fan of Cambridge United, so I've seen good managers and poor managers in my time," he told 5Live.