f disrtibution

Discussion in 'CT3' started by Visakha, May 10, 2012.

  1. Visakha

    Visakha Member

    can someone explain how to calculate F(15,15) at 0.2 level
    15,15 aint in the tables so how do we go about it?
    this is freaking me out :mad:
     
  2. John Lee

    John Lee ActEd Tutor Staff Member

    It shouldn't be in a CT3 exam as it's not possible (at least not with any accuracy) to obtain it from the Tables provided.
     
  3. Visakha

    Visakha Member

    It's a question from Nov 2008 of the Indian Institute exam.
     
  4. John Lee

    John Lee ActEd Tutor Staff Member

    Q13a - fascinating. I can only assume that the Indian students have different tables or just the people who set the exam used different tables (and hence there was a mistake in the exam). Worth pursuing with the IAI I think...
     
  5. Visakha

    Visakha Member

    no we have the same tables..
    anyways i just had a question.. suppose we need to calculate F(14,11) at 5% so can we use interpolation. If not how to we go abt it?
     
  6. Calum

    Calum Member

    It could be done (I think; I haven't tried!) by considering the F(15,15) distribution as the ratio of two chi-squared variates and using that to derive the density - messy, but looking at the equations it looks analytically possible.

    Not sure this is what the examiners were driving at though!
     
  7. John Lee

    John Lee ActEd Tutor Staff Member

    Yup - though it won't be very accurate.
     

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