PSY 280 Exam 3 – Study guide
Chapter 7
1. If you see the notation X Y  , what should
you do?
a. First multiply each X by its partner Y, then
sum the results.
b. First sum the Xs then multiply the sum of
the Xs by each Y.
c. First sum the Ys, then multiply the sum of
the Ys by each X.
d. First sum the Xs, then sum the Ys, then
multiply the sums.
2. In an experimental design __________, whereas
in a correlational design __________.
a. there is only one variable (the independent
variable); there are two variables (X and Y)
b. there are two X variables; there are an X
and a Y variable
c. researchers assign each person an X score
and then measure the score on the Y
variable; researchers measure scores on
variables that a participant has already
experienced
d. researchers measure scores on variables
that a participant has already experienced;
researchers assign each person an X score
and then measure the score on the Y
variable
3. In a correlational analysis, N stands for the
a. total number of pairs of scores.
b. total number of X scores plus the total
number of Y scores.
c. total number of X scores times the total
number of Y scores.
d. total number of pairs of scores minus 2.
4. In general, a positive correlation means that as the
values of one variable __________, there is a
tendency for the values of the other variable to
__________.
a.
b.
c.
d.
increase; increase
increase; decrease
increase; remain the same
decrease; increase
5. In a linear relationship, as the X scores increase,
the Y scores change
a.
b.
c.
d.
in only one direction.
only in the negative direction.
only in the positive direction.
in the positive and then in the negative
direction.
6. A “weak” relationship between two variables is
represented by
a.
b.
c.
d.
a small spread of Y scores at each X score.
a large spread of Y scores at each X score.
only one value of Y at each X score.
an equal spread of Y scores at each X
score.
7. Professor Helgin has found that the correlation
between the length of a person’s index finger and
the person’s IQ is 0.09. He should conclude that
a. as the length of the index finger goes up,
there is a fairly strong tendency for a
person to have a lower IQ.
b. there is no relationship between the two
variables because the r is negative.
c. we can be confident in predicting that
people with high IQs will tend to have
long index fingers.
d. there is a very weak relationship between
the length of the index finger and IQ
because r is nearly 0.
8. Calculate the appropriate correlation coefficient for the following data:
Participant
1
2
3
4
5
6
(X)
(Y)
0
2
1
3
4
5
1
3
0
1
4
6
9. Calculate the appropriate correlation coefficient for the following data.
Employee
Number of
Units Produced
(X)
Minutes Spent
in Break Room
(Y)
1
2
3
4
5
6
12
4
15
10
8
7
10
22
5
12
10
15
Chapter 8
1. Linear regression is important because
a. it is used to predict unknown Y scores
based on X scores from a correlated
variable.
b. it is used to predict unknown Y scores
based on X scores, even if the X variable is
not correlated with the Y variable.
c. it is a statistic that summarizes the
relationship between the X and Y
variables.
d. it indicates how close our predictions of Y
values are to the actual Y values.
2. Linear regression is defined as the procedure for
determining
a.
b.
c.
d.
whether a relationship exists.
the strength of a relationship.
the direction of a relationship.
the best-fitting straight line in a linear
relationship.
3. The slope of a line is a number indicating the
a. slant of the line and the Y-intercept.
b. slant of the line and the direction in which
it slants.
c. slant of the line and the X-intercept.
d. length of the regression line to be drawn.
4. What is the slope of the following regression
equation?
Y   2.69 X  3.92
a.
b.
c.
d.
3.92
3.92
2.69
2.69X
5. If there is no relationship between two variables,
the slope of the regression line will equal
a.
b.
c.
d.
1.0
0.5
0.0
1.0
6. When there is no relationship between two
variables, the value of every Y  is equal to
a.
b.
c.
d.
the value of every X.
the value of every Y.
the value of the Y-intercept.
zero.
7. At State University Medical Center, a research
study has produced a value of r = -.69 between
the number of years a person has smoked and
that person’s lung capacity. Assuming the
correlation passes the appropriate inferential
test, what should the researchers do next?
a. Nothing, as there is no relationship
between the variables.
b. Calculate the mean and standard deviation
at each value of X.
c. Calculate the linear regression equation.
d. Determine if there is homoscedasticity in
the Y scores.
8. For the following data, what is the predicted test score for a person with a stress level of 10?
Participant
1
2
3
4
5
6
Stress
Level
(X)
Test
Score
(Y)
18
3
12
8
15
7
6
17
9
22
7
11
9. In the following study, researchers wanted to determine if a relationship existed between the minutes of light
therapy a patient receives and the patient’s reported score on a seasonal affective disorder (SAD) test. What is the
regression equation for the data below?
Participant
1
2
3
4
5
6
7
8
9
10
a.
b.
c.
d.
Y
Y
Y
Y
Minutes of
SAD
Light Therapy
(X)
5
13
10
7
9
12
13
11
8
7
= –3.08X + 1.64
= 9.5 X + 12.5
= 2.69 X – –.49
= 1.64 X – 3.08
7
20
11
8
6
18
18
16
12
9
Test Score
(Y)
Chapter 11
1. When is a t-test used instead of a z-test?
a. When the population µ is known
b. When the population deals with two
samples
c. When the population standard deviation is
known
d. When the population standard deviation is
unknown
2. What happens to the t-distribution as the sample
size increases?
a. The t-distribution appears less and less
like a normal distribution.
b. The t-distribution appears more and more
like a normal distribution.
c. The shape of the t-distribution is
unaffected.
d. s X becomes nearer to the true value of µ
3. Degrees of freedom (df) for the one-sample t-test
is equal to
a. N .
b. N.
c. N – 1.
d. s X .
4. Which kind of estimation is performed when we
claim that a population mean is equal to the
sample mean?
a.
b.
c.
d.
Interval estimation
Mean estimation
Point estimation
Population estimation
5. What is the purpose of using a confidence
interval?
a. To estimate the value of a sample mean
b. To use a sample mean to estimate the
value of a population mean
c. To use a level of confidence to estimate a
sample mean
d. To use the sample mean to determine the
population level of confidence
6. The confidence interval for a single  is
a. a point interval estimation of the population
mean.
b. an interval containing values of  that our
sample mean is not likely to represent.
c. an interval containing values of  that our
sample mean is likely to represent.
d. a point on the variable at which the
population  is expected to fall.
7. If we reject the null hypothesis in a significance
test of correlation, we conclude that there is
a. a significant difference between the
sample correlation coefficient and the true
value of .
b. a significant difference between the
sample mean and the true population mean.
c. a nonchance relationship between the X
and Y variables.
d. a chance relationship between the X and Y
variables.
8. A study with 46 participants investigated whether
there was a relationship between one’s attitude
toward giving blood and the number of times
one has given blood in a year. The correlation
coefficient was r = +0.56. The rcrit is
__________ and the investigator should
__________.
a.
b.
c.
d.
+0.243; reject
0.288; reject
+0.243; retain
0.288; retain
H0
H0
H0
H0
9. If r = 0.72, what proportion of the variance in Y is
accounted for by its relationship with X?
a. 0.85
b. 0.72
c. 0.52
d. Cannot be determined from the
information given
10. Our population has a   35.5. Given the sample below, what is the value of tobt using a one-sample t-test for
an experiment?
38 40 41 37 35 38 41 39 34 35 38 42 44 37
11. Given the following correlational dataset, determine if there is evidence of a relationship, given an alpha = .05
X
2
5
8
4
6
5
1
6
3
Y
8
4
2
5
4
5
9
5
6
Ch7
1. D
2. C
3. A
4. A
5. A
6. B
7. D
8. +.59
9. -.92
Ch8
1. A
2. D
3. B
4. C
5. C
6. C
7. C
8. 12.43
9. D
Ch11
1. D
2. B
3. C
4. C
5. B
6. C
7. C
8. B
9. C
10. 2.601