ECON 422 Introductory Econometrics I
Problem Set 1: Solutions
Yiqun Chen
Department of Economics
University of Maryland
September 18, 2014
1. Complete the following statements:
n
(a)
i=1
n
(b)
i=1
xi
n
1
n
=
1
n
n
xi
i=1
(a + b) = a + b
(c) log(x y ) = lo
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In class problems some answers
January 22, 2013
1) Find the critical t values in the following cases:
a) n = 4, = 0.05 (two-tailed test) 3.182 ( 3 d.f.)
b) n = 4, = 0.05 (one-tailed test) 2.353 (3 d.f.)
c) n = 14, = 0.01 (two-tailed test) 3.012 (13 d.f.)
ECON 422 Introductory Econometrics I
Problem Set 2: Solutions
Yiqun Chen
Department of Economics
University of Maryland
October 5, 2014
1. The following is data on the number of children (kids) and the years of schooling (educ) for a sample
of six married
Econ422: Introductory Econometrics
Review for Midterm I: Concepts
University of Maryland, Department of Economics
Instructor: Yiqun Chen, Fall 2014
Note: These questions are meant to get you STARTED in preparing for the
exam. There will be NO multiple cho
University of Maryland, Department of economics
ECON 422: Econometrics I
Q04
Names:
1. Prove the followings:
(X X ) 0
( X X ) X nX
( X X )(Y Y ) ( X X ).Y XY nXY
2
2
2
University of Maryland, Department of economics
ECON 422: Econometrics I
Q15
Names:
1. Using a data on college performance, we estimated the following model for the fall and second semester for
athlete students:
trmgpa 2.12 0.900crsgpa 0.193cumgpa 0.0014
University of Maryland, Department of economics
ECON 422: Econometrics I
Q16
Names:
1. The variable smoke is a binary variable equal to one if a person smokes, and zero otherwise. Using a data set, we
estimated the following linear probability model:
smo
University of Maryland, Department of economics
ECON 422: Econometrics I
Q17
Names:
1. The effect of antidumping filing on the import of chemicals is estimated using monthly data in the following
model.
. reg
lchnimp lchempi lgas lrtwex befile6 affile6 a
University of Maryland, Department of economics
ECON 422: Econometrics I
Q19
Names:
1. (Example 13.2: change in return to education over time) A log(wage) equation pooled across the year 1978 (the
base year) and 1985 is given in the following equation:
l
University of Maryland, Department of economics
ECON 422: Econometrics I
Q18
Names:
1. The effect of individual lags in a Finite Distributed Lag Model can be estimated imprecisely because of
multicolinearity. One way to alleviate this problem is to assum
University of Maryland, Department of economics
ECON 422: Econometrics I
Q20
Names:
1. (Example 13.9: County crime rates in Northern Carolina) Using panel data on 90 counties in NC for 1981-1987
we estimate a simple version of Cornwell and Trumbull (1994
Spring 2014
ECON422 Computer Project 1
University of Maryland
Department of Economics
Prof. Razvan Vlaicu
Student Name: _
February 21, 2014
DUE Friday February 28, at 4pm, in 3114 Tydings
Computer Project 1
(Based on Computer Exercise C2.2 in Wooldridge)
University of Maryland, Department of economics
ECON 422: Econometrics I
Q14
Names:
1. Goldman and Romley studied the demand for Cedars Sinai vs. UCLA hospital by analyzing data from Medicarecovered patients in Los Angeles area. The following model is es
University of Maryland, Department of economics
ECON 422: Econometrics I
Q13
Names:
1. Using data on 13379 workers, Krueger (1993) studied the effect of computer usage on wage:
log(wage) 1.8 0.117compw 0.070comph 0.017compw.comph 0.051edu 0.0071edu.comph
University of Maryland, Department of economics
ECON 422: Econometrics I
Q03
Names:
1. We study the effect of GDP growth rate (X) on export as percentage of GDP (Y) for the United States
for the period 1961-2004. The following information is given. We wa
University of Maryland, Department of economics
ECON 422: Econometrics I
Q06
Names:
1. The following model describes the median housing price in a community in terms of amount of pollution (nox for
nitrous oxide) and the average number of rooms in houses
University of Maryland, Department of economics
ECON 422: Econometrics I
Q05
Names:
1. The following model is a simplified version of a multiple regression model to study the tradeoff between time
spent sleeping and working and to look at other factors a
University of Maryland, Department of economics
ECON 422: Econometrics I
Q07
Names:
1. We study the effect of GDP growth rate (X) on export as percentage of GDP (Y) for the United States
for the period 1961-2004. The following information is given. We wa
University of Maryland, Department of economics
ECON 422: Econometrics I
Q08
Names:
1. Consider and equation to explain salaries of CEOs in terms of annual firm sales, return on equity, (roe
in percentage), and return on the firms stock (ros in percentag
University of Maryland, Department of economics
ECON 422: Econometrics I
Q09
Names:
1. The following model is a simplified version of a multiple regression model to study the tradeoff between time
spent sleeping and working and to look at other factors a
University of Maryland, Department of economics
ECON 422: Econometrics I
Q10
Names:
1. Using research and development data, we estimated the effect of sales (in millions of dollars) on R&D
expenditures as percentage of sales:
rd in ens 2.613 0.00030sales
University of Maryland, Department of economics
ECON 422: Econometrics I
Q12
Names:
1. The following model is a simplified version of a multiple regression model to study the tradeoff
between time spent sleeping and working and to look at other factors a
University of Maryland, Department of economics
ECON 422: Econometrics I
Q11
Names:
1. Using a data set on students performance and their characteristics, we estimated the following model:
stndfnl 2.05 0.0097atndrte 1.63 priGPA 0.128ACT 0.296 priGPA2 0.0
Econometrics
Econ 422
Sergio Urzua
PRACTICE EXAM
Short Questions (30 points)
Please answer True or False. Answers without explanation will not receive credits.
(a) (6) The OLS estimator is unbiased if and only if: E (U |X) = 0 and V ar (U |X) = 2 .
(b) (6
PRACTICE QUESTIONS
1. We derived the properties of the OLS estimators. We showed that under
Homoscedasticity the estimators are unbiased.
ANSWER: FALSE.
2. We should always prefer models with large R2. That is
Econometrics I
Econ 422
Sergio Urzua
Due date: April 5, 2017
Problem Set 3
Plan to spend 10 hours (maybe more) on these questions. Total points
are 100. Please return the problem set on time. Good luck!
Question 1. Short Questions (20 points)
(a) Let D1 ,
Practice Problems for Exam I (Sintim 2015)
Provide the structures of starting materials that would undergo cycloaddition
reactions to give the following products:
CN
NC
1)
5)
CN
O
O
2)
O
6)
O
NMe
O
O
O
7)
3)
N
N
N
O
Cl
O
O
Ph
Cl
Econometrics I
Econ 422
Sergio Urzua
Due date: May 8, 2017
Problem Set 4
Plan to spend 10 hours (maybe more) on these questions. Total points are 100. Before
start working on the problem set read the STATA help for the following commands: kdensity,
ivregr
Econometrics I
Econ 422
Sergio Urzua
Due date: Feb 27, 2017
Problem Set 2
The following problem set could be a little tough. Plan to spend 10 hours
(maybe more) on these questions. Total points are 100. Please return the
problem set on time. Good luck!
Qu
Econometrics I
Econ 422
Sergio Urzua
Due date: Feb 8, 2017.
Problem Set 1
The following problem set could be a little tough. Plan to spend 10 hours
(maybe more) on these questions. Total points are 100. Please return the
problem set on time. You can work