Are the Oilers even worse this season than they were last year, when they finished 30th in a 30-team league? To mutate an old saying from graduate school, if your team is laughable then their failure is graphable. Here's a box-and-whisker plot—a form of visual shorthand used by statisticians—of game-by-game regulation-time goal differentials for the two Oiler editions:

The MEAN GD of the two teams is shown only implicitly on this diagram. By that measure this team is much worse; the Oilers were behind after 60 minutes by an average of 0.87 goals last year, whereas the number so far this year is 1.32. The boxplot, by design, shows the *median* of the data as a thick black line, and the boxes show the "interquartile" limits—they extend up to the 75th percentile and down to the 25th percentile. (You can think of this as the "middle fifty [percent]" of the games: notice that last year, the Oilers were down by zero, one, or two goals after 60 minutes roughly half the time.) The whiskers extending out from the boxes are essentially 95% confidence limits, with a few outliers peeking out of last year's data. (Those outliers themselves are kind of shocking in their pedestrian-ness—the dots above the whisker represent a 6-1 drubbing of Nashville and a 4-0 shutout of Phoenix, and the one below was a 6-0 loss to the Avs.)

It's too soon to say whether the Oilers are definitely worse than last year, as the fairly even positioning of the boxes suggests. Their penalty-kill, however, can now be said to be significantly worse in a statistical sense. Last year they killed 78% of their penalties, good for 26th in the league. So far this season they have escaped without a goal on only 58 of 86 occasions (67.4%) in which they have been short-handed; if their true penalty-killing ability was 78%, this would happen only 1 time in 64 by chance. But anybody who has watched the games knew the unspeakable truth already.

## Comments (3)

Wait, are we talking about Les Petroliers de Québec?

Posted by Soltesz | December 2, 2010 12:04 PM

Posted on December 2, 2010 12:04

Do you get the feeling the Oilers, in the four days following this post, went 3-0 over three games including a 5-0 shellacking just to spite you?

Posted by FACLC | December 3, 2010 11:02 PM

Posted on December 3, 2010 23:02

Like the saying goes, within the guru's head there aren't many scenarios, but for a person with a rookie's mind, the entire world is open.

Posted by Natalia Cecot | December 14, 2010 7:34 AM

Posted on December 14, 2010 07:34