Penalties: how many are taken and how often are they scored?

I asked the nice people at Infostrada Sports Group for a whole slew of data with regards to penalties taken in the Premiership and they were kind enough to provide me with it. They can be found online and on twitter.

When I requested this data I had one particular idea in mind (that post looks pretty cool and will come later) but there’s a lot of interesting stuff in there so I thought I should do a proper job of using it. Today’s is nice and simple; a couple of plots summarising penalties on a seasonal basis.

Firstly, the number of penalties awarded each season and their contribution towards the total number of goals scored each season:

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So penalties account for roughly 7% of Premiership goals and a typical round of fixtures will see two being scored.

The top line has two distinct features. The first is an upward trend, which kind of matches up with the increase in shots that has occurred over the same time period (link). Both of these suggest that Premiership football seems to be more attacking in nature now than ten years ago. The second distinct feature is the two spikes corresponding to the 2006-07 and 2009-10 seasons. I’d posture that these are the result of a rule change or extra scrutiny of referee performance these seasons, can anyone back me up or add some context here?

Secondly let’s see how successful players have been at converting/saving penalties historically:

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There has been a remarkable level of consistency here – 8 of the 11 seasons fall between 76 and 80% conversion. There was a drop off in conversion this season ( down to 72%), equivalent to about five penalties being saved or missed compared to an average season. There is, however, no reason to expect this trend to continue and the odds of next seasons conversion rate being lower than this seasons are about one in seven. If I had to guess the conversion rate next season I’d be going with the 77% historical average.

Next time I’ll look at how penalties are distributed as a match progresses, and see whether those taken later in the match are as likely to be scored as those taken early on.

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