The past tells us precious little about future Premier League goal times

Manchester United have not scored in the first 15 minutes of a Premier League game this season. They have scored only twice in the first half-hour. They scored 12 times in the second half-hour and 12 times in the third half-hour.

When United play again I might see one of those stats pop up on my television screen. The commentator could say United start games slowly. What they should say is that United have started games slowly.

The difference might sound small but it can be hugely important. It is the difference between what happened in the past and what will happen in the future. It is why people who see standout stats and put them into bets lose more money than they win.

Aston Villa have scored three goals in the first half-hour of matches, six in the second half-hour and 14 in the third half-hour. Manchester City have conceded once in the opening 45 minutes, eight times in the closing 45 minutes.

Often when I am watching a match on television a stat will flash on my screen showing how many goals a team have scored or conceded in the period about to begin. I might turn on the sound to hear the commentator say we are entering the period of a match when this team do well. It is not the period when they do well, it is the period when they have done well.

Looking through my records I feel I could come up with such a stat for every Premier League team. Are they all genuinely unusual? Or is there simply a lot of randomness in the times goals are scored, meaning that how they are scattered in one set of games might be very different from how they are scattered in another? I believe the second answer is the right one.

We are approaching the midway point of this season. I looked at what happened in the first and second halves of previous seasons. I did this for the 24 Premier League seasons from 1997-98 to 2020-21. I divided each match into 15-minute segments: minutes one to 15, 16 to 30, 31 to 45, 46 to 60, 61 to 75 and 76 to 90. I counted how many goals a team scored in each segment in the first and second half of the season. And then I compared them.

The correlation was weak. It varied from segment to segment but mostly it was around 0.2. What does that mean? If what happened in the first half of a season was reproduced exactly in the second half the correlation would be 1.0. If there was no relationship between what happened in the first and second halves of a season the correlation would be 0.0. It was much nearer zero than one.

Some teams are better or worse than others, and they should score different numbers of goals from others in all periods of matches – they should have done so in the past and, whether they did or not, they should do so in the future.

Generally speaking, more goals have been scored in the later stages of matches than in the earlier stages. There is one exception, which you will see in the next figures and I will explain afterwards – though you could easily have worked it out for yourselves.

Over the last 24 completed seasons 13 per cent of goals were scored in the first quarter-hour, 14 per cent in the second quarter-hour and 17 per cent in the third quarter-hour (after which there was an interval), then 16 per cent in the fourth quarter-hour, 17 per cent in the fifth quarter-hour and 23 per cent in the sixth quarter-hour (after which matches ended).

I have spoken about 15-minute periods but in reality the last one in each half lasts longer. After those 15 minutes have been played the referee adds time to compensate for stoppages. This is why there were more goals at the end of the first half than at the start of the second half. And why there were so many goals at the end of the second half. Otherwise, as you can see, the number of goals rose steadily throughout matches.

As I said, some teams are better than others and some teams are worse than others. Some teams will score more goals than others and some teams will score fewer goals than others. But no matter how many goals any team score from now on they are likely to get 13 per cent of them in the first quarter-hour of matches, 14 per cent in the second quarter-hour, and so on. No matter what the percentages were in the past, this is what they are likely to be in the future.

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