P1.T2. Miller Chapter 7 Questions

[chiaaugu]

Hi all

I have some pretty basic queries which I would appreciate some help on:

1) Looking at the first Stock & Watson example (Pg 84) , why did we use 1.972 instead of 1.96 as the z value?

2) Question 209.1 - how is the standard deviation obtained? The answer sheet stated that SD= SQRT(15% * 85%/60). Not very sure where these values come from....

3) I am guessing the exam will not be providing us a T table... how are we then expected to answer some of these questions? Would they only ask questions with 90/95/99 significance?

 

[ShaktiRathore]

hi
regarding third question,
please see: https://forum.bionicturtle.com/threads/distribution-tables.7382/#post-26762 and https://forum.bionicturtle.com/threads/z-table-during-the-exam.5443/
plase use serach option is very handy if u have any queries .
thank

 

[brian.field]

1) Looking at the first Stock & Watson example (Pg 84) , why did we use 1.972 instead of 1.96 as the z value?
The 1.972 is the exact number assuming a t distribution (in excel, it is =TINV(0.05,n-1) which is =TINV(0.05,199))
It really doesn't matter if you use t or z when dealing with n=200. If n was 30 or a small number, it would be more important to use t.

2) Variance for a bernoulli is p*q = p*(1-p) where in this case, p = 0.15 and q = 1 - p = 0.85 and the standard deviation is the square root of that. Remember that the standard error is = standard deviation / sqrt(n), so sqrt(p*q) / sqrt(n) which is equivalent to sqrt (p*q/n)

 

[Nicole Seaman]

Hi all

I have some pretty basic queries which I would appreciate some help on:

1) Looking at the first Stock & Watson example (Pg 84) , why did we use 1.972 instead of 1.96 as the z value?

2) Question 209.1 - how is the standard deviation obtained? The answer sheet stated that SD= SQRT(15% * 85%/60). Not very sure where these values come from....

3) I am guessing the exam will not be providing us a T table... how are we then expected to answer some of these questions? Would they only ask questions with 90/95/99 significance?

Hello @chiaaugu

Regarding your second question, the original practice question and discussion is located here: http://forum.bionicturtle.com/threads/p1-t2-209-t-statistic-andconfidence-interval.5318. Please make sure to use the links that are provided in the question sets to ask questions. You may find that your question has already been answered in the discussion. If your question has not been answered, please make sure to post any other questions in that specific thread. This keeps our forum organized so you and other members can find answers quickly.

Thank you,

Nicole

 

[chiaaugu]

Thanks all.