CS1 Chapter 9: Question 4(i)(c)

Discussion in 'CS1' started by Noely, May 4, 2020.

  1. Noely

    Noely Member

    Hi - I was hoping to get some help in understanding what is happening in this question. The data is paired data with a total of 17 observations. Why do we use the formula for estimation of normal variance in this instead of the Paired data formula?

    upload_2020-5-4_19-44-34.png
    Am I correct in the assumption that it is because paired data can be treated as a single sample problem? Or is there something that I am missing?

    Thank you.

    Regards
    Noel
     
    Last edited by a moderator: May 4, 2020
    Noely, May 4, 2020
    #1
  2. John Lee

    John Lee ActEd Tutor Staff Member

    The P stands for pooled not paired - ie since the variance is assumed to be the same for both groups we pool all 17 results together to estimate the variance from that.

    For a CI we adapt the formula on p22 of the tables to swap \((n-1)\) to \((n_1 + n_2 -2)\) to match the degrees of freedom.
     
    John Lee, May 4, 2020
    #2

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