Advertisement
If you have a new account but are having problems posting or verifying your account, please email us on hello@boards.ie for help. Thanks :)
Hello all! Please ensure that you are posting a new thread or question in the appropriate forum. The Feedback forum is overwhelmed with questions that are having to be moved elsewhere. If you need help to verify your account contact hello@boards.ie
Hi there,
There is an issue with role permissions that is being worked on at the moment.
If you are having trouble with access or permissions on regional forums please post here to get access: https://www.boards.ie/discussion/2058365403/you-do-not-have-permission-for-that#latest

Stats Question: x is not a deviate from the normal distribution

  • 26-05-2009 9:11pm
    #1
    theprodigals0n
    Closed Accounts Posts: 24 ✭


    Hey all,

    I have an exam tomorrow, and can't seem to get my head around one question. Not sure how to word this exactly, but basically if x = (the sum from 1 to 12 of u) - 6, where u is iid normally distributed, how do you prove that x is not a deviate from a normal distribution function?

    I think I may have the answer, but it looks incorrect to me, so I figure I took it down wrong. The answer I have is that if F(x) is the cdf for x then F(6)=1 which is greater than the value of 6 of the cdf of a standard normal. But surely the value of 6 for the standard normal is also equal to one in this case, as it's the end point?

    I have the exam tomorrow morning, so any help would be greatly appreciated.


Comments

  • #2
    silverside
    Registered Users, Registered Users 2 Posts: 1,372 ✭✭✭silverside


    sum of normals *is* normal

    check the wording again ?

    edit : if you want to show that it's not N(0,1) then look at Var(u) which is clearly 12 and not 1. You can show this in tedious details by explicitly writing out the variance from first principles if needs be.


Advertisement