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Counts of the number of broken bones in college athletes during the season would be best represented by which of the following probability models?

Question options:

  1. Binomial --Thinking this is the best answer since they either yes broke a bone or no did not break a bone
  2. Poisson
  3. Uniform
  4. Normal (This is not the correct answer)
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    $\begingroup$ Can you specify your question, as distinct from the homework question you were given? What is it you are confused about? Be aware that our policy is not to answer your homework questions for you, but to provide hints to help you think through where you're stuck. You may want to read our FAQ. $\endgroup$
    – gung - Reinstate Monica
    Sep 25, 2012 at 4:09

1 Answer 1

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This is count data. That rules out uniform (continuous or discrete) as well as normal. The only possibilities based on data type are the Poisson and the Binomial. The binomial does not seem appropriate because this is not the number of outcomes for a fixed number of independent experiments where each of n people can have their bone broken with the same probability. The Poisson fits because it represents certain rare event hypotheses and is a number of broken bpne events observed over a given interval of time (ome football season). It is not clear that the Poisson is the best model but it is better than the other choices. The number of college football players in finite so there is a fixed finite limit to the number of events when technically the Poisson has no limit.

If someone argued for the binomial because there is a fixed finite number of players available at the beginning of the season that are at risk for injury from a borken bone on any individula play and the plays are independent. Then the trial could be considered the plays and with 22 players available on the play may indicate a constant probability that a broken bone will occur on the play. The problem with that argument is that the number of plays in a season is not known and should be considered random (unless you look ay this conditional on the number of plays that actually occurred during the season). The other issue is that plays differ in the injury risk. Real life situations can always lead to arguments against a model but the shear randomness and rarity of bone breaks points to the Poisson as the best model of the 4 choices.

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  • $\begingroup$ Please review our policy about answering homework questions, Michael: faq. $\endgroup$
    – whuber ♦
    Sep 25, 2012 at 8:23
  • $\begingroup$ @whuber You know that I understand the policy. This is a tricky question and it is hard to give a helpful answer to a multiple choice question without giving an opinion about what I think is the right choice. Maybe my best option was not to answer at all. I do think a case could be made for binomial even though it is a weak case. i didn't like the answer when I wrote it because it was late at night and I thought my rationale was a little confusing. I will think about deleting it. But II think I should let other people let me know what I should do by the way they vote. $\endgroup$
    – Michael R. Chernick
    Sep 25, 2012 at 11:25
  • $\begingroup$ @whuber Do you think there is a way that I could edit my answer to get some points across and still conform well to the site's policy on home work? $\endgroup$
    – Michael R. Chernick
    Sep 25, 2012 at 11:28
  • $\begingroup$ This is clearly a homework question as noted in Zen's comment. But the OP has not added the label. Zen's comment about the Poisson seems to tell that he thinks that Poisson is the correct answer. Doesn't that also violate the site's policy. Multiple choice questions are difficult to deal with. $\endgroup$
    – Michael R. Chernick
    Sep 25, 2012 at 11:40
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    $\begingroup$ One of the best and easiest options is to ask the OP (in a comment) what efforts they have made towards solving this problem. Not only will that focus the question and perhaps make it acceptable here, it will make us all better aware of what kind of answer will be most helpful and what level to pitch it at. If that request (issued politely, of course) gets no response, then the question needs to be closed rather than answered. Because I notice that @gung made that effort and the OP has logged on since then without editing the question, it is my duty as a moderator to close it now. $\endgroup$
    – whuber ♦
    Sep 25, 2012 at 21:26

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