Yes, it's everybody's favourite pastime: talking about referees.
Conventional wisdom states that refereeing controversies are, in large part, avoidable. If only referees were prepared to front up and explain their decisions to the media after a game, then you could clear up controversial incidents at a stroke. Managers do the same, and virtually nobody ever talks about them.
Jose Mourinho has been charged by the FA for claiming that Premier League referees have a conspiracy against Chelsea. Mourinho has form in this regard: a few years ago, at Real Madrid, he suggested that Barcelona, referees and Unicef were engaged in a three-way conspiracy against him, which if nothing else evoked an agreeably surreal image. Imagine the meetings.
But this column is nothing if not open-minded. If an upstanding member of the football confraternity thinks there's foul play afoot, then it's our duty to investigate.
For this table, we looked at teams who had played in at least three of the last five Premier League seasons, including the current season. That's 19 teams in total.
In large part, the categories give an insight into styles of defending. For example, Southampton have the ninth highest foul rate, but one of the lowest card and penalty rates, probably because they commit a lot of their fouls high up the pitch. Arsenal are the opposite - they don't commit too many fouls, but when they do, it's generally a pretty big deal, which fits the impression of Arsenal as the sort of team who defend with one hand covering their eyes.
Chelsea? They commit an average number of fouls, and yet have fewer penalties awarded against them than any other team in the Premier League over the last five seasons. But before you dismiss Jose's concerns out of hand and place him in a box with "9/11 Truthers", "Hitler Conspiracy Theorists" and David Icke, these tables don't tell you a huge amount on their own. Maybe John Terry and Gary Cahill are just exceptionally good at tackling in the penalty area. Maybe the Stamford Bridge turf offers exceptional grip. Perhaps we should dig a little deeper.
In 2001, a bunch of academics from the University of Chicago and Brown University caused a stir when they published a paper called "Favouritism Under Social Pressure" (PDF). They looked at 760 La Liga games from the 1990s, and found that when the home team was a goal behind, referees awarded twice as much injury time as when the home team was a goal ahead. They found that after three points were introduced for a win in the mid-1990s, the effect became even more pronounced.
But that was almost two decades ago. Referees are tested to far more rigorous standards today. Injury time is calculated not by the main referee on the field, but by the fourth official on the touchline, and displayed on a screen to everyone in the stadium and watching at home. Besides, this is the English Premier League, the EPL, the BPL, home of honesty, integrity and fairness in football since 1992. You wouldn't get that sort of continental skulduggery over here, would you?
Looking again at Opta data on added time after 90 minutes in the Premier League since the start of the 2010-11 season, we worked out that the average amount of time added on at the end of a game is 4 minutes and 17 seconds. Keep that in mind.
We decided to adapt the 2001 experiment for a modern Premier League context by focusing on the biggest clubs. We focused on probably the five biggest clubs of the last five seasons: Arsenal, Chelsea, Liverpool, Manchester City and Manchester United. Fans of smaller clubs often claim that the big teams get more injury time when they need it. "Fergie Time" became one of the most powerful psychological forces of the Premier League era, right up with "mind games", the "dreaded second season" and "Stoke on a wet Tuesday night".
But how much reality lies behind the myth? Quite a lot, as it turns out. The next graph shows the amount of injury time the big five teams can expect when playing in front their own fans, depending on how the game is going. And it's quite a big difference.
The closer a game is, the more injury time is played. That's understandable - how many times have we seen referees ending thrashings just a second or two early, perhaps to protect the dignity of the losing team, or simply because everyone's lost interest. But there appears to be a significant bias towards big clubs when the game is still in the balance. If you're playing at one of the big clubs and you're two goals down, you get an average of 3 minutes and 45 seconds to claw back the deficit. If you're two goals up, the big club gets more than five minutes to try and break you down.
Now, let's look at how things break down club by club.
Injury time played by game state, 2010-date
Which pretty much fits the above pattern. Arsenal can expect more than a minute of extra injury time if they are losing, compared to if they are winning. Liverpool can expect almost two minutes extra. If you were to extrapolate that over 19 home games a season, that adds up to nearly an entire extra half of football.
It's worth pointing out that some of the numbers are volatile because of the low sample sizes involved. Manchester City's injury time when losing after 90 minutes at home looks a little on the low side, but because it's only happened six times in the last five seasons, there's not enough data to draw any firm conclusions.
On one of those occasions, you may remember, this happened.
Chelsea, like other big clubs, benefit from the same phenomenon. On average around four minutes of injury time is played when they're winning. If they're losing, they get more than a minute extra.
All of which points to one conclusion: if there is a conspiracy, as Jose Mourinho suggests, he should probably keep quiet about it. Because his side are benefiting.
All data based on Opta stats for Premier League games played since the start of the 2010-11 season