1. CU77
    March 23, 2017 @ 8:55 pm

    “but both assisted and unassisted goals have a positive expected value, meaning in addition to the goal scored, the model says you should expect .03 to .04 goals in the next 60 seconds. It’s tiny, but this speaks to the value of momentum?”

    Or it’s a statistical fluctuation? What’s the estimated error on this number?


    • Lacrosse Reference
      March 23, 2017 @ 9:12 pm

      What kind of error metric did you have in mind? In terms of the raw data (table also included at the bottom of the post), there were 9,819 assisted goals and 7,565 unassisted goals in the data set, so the sample size is substantial.


  2. CU77
    February 6, 2018 @ 12:46 pm

    Let’s take the 9819 assisted goals. If I’m understanding your table correctly, the team that scored went on to score another goal in the next minute 1479 times, and the team that was scored on went on to score a goal in the next minute 1115 times. Assuming goal-scoring is a Poisson process, the standard-deviation error on each number is the square-root of each: 38.46 for 1479, and 33.39 for 1115, and these errors are independent. The difference 1479-1115=364 then has an error which is the square root of the sum of the squares of the errors on each number, which is then the square root of sum 1479+1115=2594; this is 50.93. The difference 364 is 7.15 times the standard deviation 50.93, and is therefore very unlikely to be a statistical fluctuation.

    This is the sort of error analysis I wish you would do. Merely saying “the sample size is substantial” is not enough to draw any actual conclusions, you have to work through the numbers.


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