Friday, 15 August 2014

Puckerings archive: Effect of Rest of NHL Team Performance (10 Sep 2001)

What follows is a post from my old hockey analysis site (later It is reproduced here for posterity; bear in mind this writing is over a decade old and I may not even agree with it myself anymore. This post was originally published on September 10, 2001 and was updated on November 12, 2002.

The Effect of Rest on NHL Team Performance
Copyright Iain Fyffe, 2002

What effect does the amount of rest an NHL team has before a game have on the outcome of the game? We would probably expect that the more rest a team has, the better they will do. However, there is the possibility of too much rest leading to teams being “rusty”, and not performing as well. This simple study examines this question.

Using data from 1998/99 and 1999/2000, I compiled the records of all NHL teams based upon the number of days off since their last game. For comparability’s sake, I ignored the “1 point for an OT loss” rule that came into effect in 1999. Here are the results:

 Tot  Tot  98/99  98/99  99/00  99/00
 Days rest  GP  Pct  GP  Pct  GP  Pct
 0  850  .450  410  .456  440  .444
 0  850  .450  410  .456  440  .444
 1  2130  .503  1041  .500  1089  .506
 2  899  .526  463  .531  436  .521
 3  378  .525  180  .492  198  .556
 4  130  .519  60  .575  70  .471
 5 or more  70  .600  33  .530  37  .662

The results match our expectations quite well. Teams perform the worst when they played the night before, having no time off. There is some suggestion that too much time off may not be good, since at four days off there is a drop in winning percentage. It is a small drop, and is probably not statistically significant. But remember, we would actually expect an increase in percentage, so it seems the benefits of additional rest are offset by the effect of rust, shall we say.

There is one more interesting thing to note in this study. The average NHL team had 108.3 days of rest between their first game of the season and their last game. This average is identical in 1998/99 and 1999/2000. However, the range of days off among teams went from (103,112) in 1998/99 to (104,111) in 1999/2000, and the standard deviation dropped from 1.8 to 1.4 days. Therefore, the NHL schedule got a little fairer in 1999/2000, with teams having more similar amounts of days off.

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