Q: How safe is a lead after each period in the NHL?

A: Reasonably to very.

Posted by Mike Apted on Thursday, January 7, 2016

After discovering SDQL I’ve been working to pick up the basics of the query language. Best to start with something easy and work up from there I figure, so the first question I wondered was:

How safe is a lead after each period in the NHL?

Using KillerSports.com as my source (the data goes back to 2006) and filtering for regular season only that answer seems to be: Pretty safe. Teams taking a lead of any kind into the first intermission win 75% of those games. If they hold a lead after two periods that winning percentage jumps to 85%. A 4+ goal lead at any point is a virtual lock, and contrary to popular opinion a one goal lead seems to be the “most dangerous” differential (unsurprisingly) with a winning percentage approx 5% below the “any lead” totals.

The results stack up like so:

Goal Diff / After Period >0 1 2 3 4 5
1st 74.6% 69.1% 84.3% 91.9% 98.9% 100%
2nd 84.8% 75.4% 90.7% 97.1% 99.4% 100%

Examples of the basic SDQL used to generate these results (updating the goal differential) was:

period scores[0] - o:period scores[0] = 1 and playoffs = 0


(period scores[0] + period scores[1]) - (o:period scores[0] + o:period scores[1]) >= 0 and playoffs = 0

As I get more comfortable with SDQL I am hoping I can find some more insightful questions to answer, but this was a good “get your feet wet” first step.