Econ 210 Spring 2007 Second Midterm - Solutions

Econ 210 Spring 2007 Second Midterm - Solutions -...

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Northwestern University Department of Economics STAT 210 Introduction to Statistics - Professor: Steffen Habermalz Second Midterm Examination – May 11 th 2007 INSTRUCTIONS : Please read the whole exam first. Questions are not ordered by difficulty. Answer all questions. Make sure you show ALL your work. Merely reporting the correct answer will not result in full credit. Write legibly. If we can’t read it we won’t grade it. GOOD LUCK! 1. (5 pts.) Write your name and circle your TAs name on the answer sheet. 2. (2+3=5 pts. each) True/False: State if the following statements are true or false. Only clearly explained answers earn full credit. a. With N=1000 the following holds ( 29 ) , 0 ( ~ 2 X X N X N σ μ - TRUE. ( 29 ( 29 ( 29 0 X X E N X N E X - = - = and ( 29 ( 29 ( 29 2 ( ) X X X V N X N E X N V X - = - = = b. If X~N(8,49) and N=10 then ( 29 5 . 0 8 = X P TRUE. When X is normally distributed the sample mean is, too, regardless of N. Since the distribution in symmetric the result follows. c. If X~N(8,49) then the interquartile range (IQR) is equal to 9.45 TRUE. Calculate P(X<a)=.25 P(X<b)=.75. IQR=b-a d. An unbiased estimator cannot be inconsistent TRUE. The Law of large numbers states that a sample average (estimator) converges to its expectation when the sample size grows. An unbiased estimator is equal to that regardless of sample size and therefore consistent. e.
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This note was uploaded on 09/25/2010 for the course ECON 210 taught by Professor Pavan during the Winter '09 term at Northwestern.

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Econ 210 Spring 2007 Second Midterm - Solutions -...

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