Hockey Outsider
Registered User
- Jan 16, 2005
- 9,490
- 15,791
INTRODUCTION
As promised, I've done another analysis of secondary assists. All of the previous studies done in this area, including mine, have looked at the data using the same conceptual approach - examining year-over-year correlations. In other words - does knowing how many secondary assists a player records in YEAR X allow us to better estimate how many secondary assists, total assists, or points, a player will record in YEAR X+1. (The answer is pretty clear - yes it helps us predict points in the future, but not as well as goals or primary assists).
For this study, I've analyzed the data in a completely different way. To the best of my knowledge, nobody has done this type of analysis before. The question that I was trying to answer is - does knowing how many secondary assists a player records help us predict how well his team scores when he's on the ice?
An example might help illustrate this concept. Let's say two players have the following stat lines:
Player 1: 30 goals, 25 primary assists, 25 secondary assists
Player 2: 30 goals, 25 primary assists, 10 secondary assists
What we really care about is - does Player 1's team do better when he's on the ice, compared to Player 2? If, as some have argued, secondary assists are just statistical noise, then we'd expect that knowing how many secondary assists a player records wouldn't improve our predictive ability. If secondary assists are more than just statistical noise, then knowing the number of secondary assists a player earns would improve the accuracy of our predictive models. (Obviously, looking at only two players is meaningless - there's way too much context not taken into account - but I'm going to look at thousands of data points).
My approach is as follows. First, I'll definite the sample and validate the data. Second, I'll estimate how many 5-on-5 goals a player should be on the ice for, once we know his 5-on-5 goals and primary assists. Third, I'll do the same analysis, except this time I'll also use secondary assists, and see if we get a more useful prediction model.
The conclusion - which will soon be obvious from the data - is secondary assists have informational value.
As promised, I've done another analysis of secondary assists. All of the previous studies done in this area, including mine, have looked at the data using the same conceptual approach - examining year-over-year correlations. In other words - does knowing how many secondary assists a player records in YEAR X allow us to better estimate how many secondary assists, total assists, or points, a player will record in YEAR X+1. (The answer is pretty clear - yes it helps us predict points in the future, but not as well as goals or primary assists).
For this study, I've analyzed the data in a completely different way. To the best of my knowledge, nobody has done this type of analysis before. The question that I was trying to answer is - does knowing how many secondary assists a player records help us predict how well his team scores when he's on the ice?
An example might help illustrate this concept. Let's say two players have the following stat lines:
Player 1: 30 goals, 25 primary assists, 25 secondary assists
Player 2: 30 goals, 25 primary assists, 10 secondary assists
What we really care about is - does Player 1's team do better when he's on the ice, compared to Player 2? If, as some have argued, secondary assists are just statistical noise, then we'd expect that knowing how many secondary assists a player records wouldn't improve our predictive ability. If secondary assists are more than just statistical noise, then knowing the number of secondary assists a player earns would improve the accuracy of our predictive models. (Obviously, looking at only two players is meaningless - there's way too much context not taken into account - but I'm going to look at thousands of data points).
My approach is as follows. First, I'll definite the sample and validate the data. Second, I'll estimate how many 5-on-5 goals a player should be on the ice for, once we know his 5-on-5 goals and primary assists. Third, I'll do the same analysis, except this time I'll also use secondary assists, and see if we get a more useful prediction model.
The conclusion - which will soon be obvious from the data - is secondary assists have informational value.