Sept 2007 Q7

Discussion in 'CT4' started by hitme, Sep 5, 2008.

  1. hitme

    hitme Member

    Part (i) a).

    I'm happy with the actual Question & Answer, but I'm confused by something that may affect my deeper understanding of the topic.

    If the statistic is based on the first 10 games that any player plays, then we would expect the maximum exposure for any player to be 10 games. The examiners report seems to indicate that the 4 players who completed 12 matches without receiving a red card are not being censored after their 10th match. This obviously doesn't impact the question, as noone is recorded as receiving a red card after their 7th match, but would matter if someone were to be red carded during their 11th or 12th match.

    Just looking for clarification really, as I want to make sure I'm understanding the topic.

    Thanks
     
  2. John Potter

    John Potter ActEd Tutor Staff Member

    Hi Hitme,

    I'm not concerned by your deeper understanding of the topic, you seem to be keeping a close eye on the censored data which is good. I think you may have a point.

    I think this is more a case that we have done more work than is actually required. ie we have all the data we need to produce a Kaplan-Meier estimate up to time 12. So the players who played all 10 games are not really censored at time 10. We then just use part of this estimate, ie S(10).

    S(10) is not affected by anything that happens between times 10 and 12, so it wouldn't really matter if we deliberately lost some information from the experiment, ie actually censored the data ourselves at time 10.

    Good luck!
    John
     

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