EC 41, UCLA Winter 2009
Name (print)________________________________
Final Exam - Version A
– 3/20/09
TA: Name__________________________ & Section Time_____________
- Only pens, pencils and erasers may be used, this is a closed book, closed note, exam.
- Students may use a calculator, but nothing that can access the internet.
- Write non-integer answers to 3 significant digits, e.g., 333, or 3.33 or .0333
- This exam consists of 20 True/False (20 points), 10 short answer (30 points) and 5 longer questions (50 points)
- Clearly write answers on this exam.
No points are awarded for illegible answers.
- Be prepared to show a photo ID during the exam (e.g., UCLA ID)
- You may leave when finished.
Do not disrupt those still taking the exam.
I. Circle T for True or F for False (1 point each)
1)
T or F
For a least squares regression, if
x
x
μ
=
and
y
y
=
; then
1
1
0
0
β
<
<
b
implies
b
2)
T or F
For a least squares regression, the standard error of the “
estimated value of the mean response,”
is always
larger than the standard error of the
“estimate value of the response variable, y.”
3)
T or F
Consider n individuals who take a pre and post test.
The t-calc for a
matched pairs t-test
will be larger than
the t-calc for a
two sample t-test assuming unequal variances
.
4)
T or F
The p-value from Excel regression output assumes a one-sided alternate hypothesis, H
A
5)
T or F
It is only theoretically appropriate to perform a least squares regression if true values of y can be entirely
explained by changes in x, so all population observations lie on the straight line for the true population.
6)
T or F
The estimate of a regression intercept will have smaller standard error if the sample mean of X is closer to 0.
7)
T or F
A least squares regression of Y on X assumes that X is measured without error.
8)
T or F
If X and Y have the same standard deviations, s
X
= s
Y
, then the slope of the reverse regression must be the same
as the slope of the forward regression.
9)
T or F
If there are 9 observed changes in a variable after treatment, seven increases and one decrease, then the p-value
from the sign test where H
0
: Median = 0, against H
A
: Median > 0 (there was an increase after treatment) = .03516
10)
T or F
If all observed data points lie on a straight line, the regression slope b will equal one.
11)
T or F
For any lease squares regression line, if the independent variable X is one standard deviation above the mean
of X, the corresponding predicted value of Y can
not
be less than one standard deviation above the mean of
Y.
12) T or F
If the random variable Z = X + Y, then the mean of Z is the sum of the means of X and Y (
μ
Z
=
μ
X
+
μ
Y
)
13) T or F
If two events are disjoint, then they have no outcomes in common.
14) T or F
A confidence interval gets wider (larger) as the level of significance,
α
, is reduced.
15) T or F
If two investments had perfect negative correlation so correlation between their returns = -1, it would be
theoretically possible to form a portfolio with no risk (standard deviation and variance = 0).