Trendspotting

The number of cards issued in Premier League games varies according to the ­difference in ability between the teams. Our expectations when betting should, therefore, alter depending on who is playing whom in individual matches.

In most bookings markets, 10 points are awarded for each yellow card and 25 for each red. The average make-up for all Premier League games played during the past 10 seasons was 36. However, if you plotted a graph showing how bookings make-ups varied with the difference in league positions between teams, it would trace an arc, highest in the middle where the difference in league position is minimal, and its lowest points at the ends where the difference in league position was greatest.

In games between teams separated by no more than two places in the final table, the average bookings make-up was 41. However, in games featuring a home team that finished more than 15 places below the away team the average bookings make-up was just 33. And in games featuring a home team that finished more than 15 places above the away team it was no bigger than 30.

The number of cards a team receive during a game is related primarily to how much defending they have to do. It follows that in evenly balanced contests, both teams are likely to receive the same number of cards.

As games become progressively more lopsided, the best team are likely to receive fewer cards and the worst team more. In our arc, the number of cards received by the best team goes down faster than the number of cards received by the worst team goes up. Hence the total number of cards in a game decreases as the difference in ability between the two teams increases.

On Sunday, Manchester United play Chelsea. Ultra-competitive fixtures are likely to produce a comparatively high number of cards. In fact, there is usually an even greater intensity about Manchester United v Chelsea because of the rivalry between the clubs. But bettors should be looking for games when the opposite applies. Over the next fortnight, Chelsea and Liverpool will both play Stoke while Manchester United and Arsenal will both play Bolton. In less keenly contested fixtures, there are likely to be comparatively few cards.

• Kevin Pullein is football tipster for the Racing Post