Hockey Analytics – Other Bits

Okay, there are a few other things that can be included in the hockey analytics umbrella, so this post will briefly glance over them.

Sample Size – This is always a criticism of statistics in general. How big is a good sample size? Some would argue that one game is surely not enough, neither is a playoff series, nor is a season.

Even strength – not a statistics per se, but the majority of statistics are gathered during even strength play. A game is at even strength when both teams have the same number of players on the ice (5v5, 4v4, 3v3), but 5v5 is the best situation to give clearer results. A power play (or man advantage) happens when team B receives a penalty and team A has one more man on the ice e.g. 5v4. Conversely, team B will be on the penalty kill, or are considered shorthanded, as they have one less player on the ice. There is also a term called score close. During the 1st or 2nd period, it is when the game is tied or there is only a one goal difference. In the third period, it is only when the score is tied. Nil-nil is included in this. In an experimental sense, 5v5 close can be considered a control, a penalty kill or power play can be considered as experimental variants.

Score Effects – Removing score effects provides more reliable Corsi and Fenwick data over time. When a team has a lead greater than one goal, particularly in the third period, it alters play, and the winning team becomes more defensive. In soccer, this is known as parking the bus. In an attempt to level the score, the losing team begins to make an increased number of shots, maybe a little bit more wild and ambitious, and spend more time in the offensive zones, and there may also be a possession shift. This skews the data so that is also why data is examined when the score is tied.

Goalies – It’s hard to measure a ‘successful’ goalie. Measuring just losses is not fair on a goal keeper as it’s too team dependent, and goal against average isn’t fair for either as the goalie can’t control how many shots he’ll face. Save percentage is used because it doesn’t punish great goalies on bad teams, and using even strength save% eliminates the quality of special teams.

Scoring Chance – Basically, it is any attempt to score a goal from a slot (the area between the faceoff circles directly ahead of the goalie). This data isn’t released by the NHL to the public, whereas the majority of the rest is. It’s a way to differentiate between shots that should be quite easy to save and ones that are not easy saves.

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